Need A/C advice

[bohman]

We have a 2009 Vue with an intermittent A/C problem that has been hard to figure out. Thought I'd run it past you guys and see if anyone had an idea.

The air conditioner functions perfectly during everyday, around town driving. In fact, it's ice cold, very nice. But if you take the vehicle on a longer trip, more than about 2 hours, it shuts off. Basically, it's icing over, except it's not actually icing over - it shuts off automatically when the condenser (or whatever part of the a/c actually gets cold, I could be using the wrong terminology) gets below a certain temp. The blower fan is still moving air, but the compressor has been turned off, so the air the blower is moving is hot air.

If you turn off the a/c and let things warm back up, then it will turn on and function perfectly again, until the cycle repeats.

I've taken it to a mechanic, he hooked up diagnostics to the a/c and reported everything functioning a-ok. No freon leak, nothing unexpected. At the time, we discovered that I have a cabin air filter that was filthy, so we figured the a/c wasn't getting enough airflow and that's why it was getting too cold.

The cabin filter was just replaced about a month ago, so it shouldn't be due for replacement yet, but we are running into the same problem on a long trip right now. We've tried running it only on recirculate, hoping that would bypass the cabin filter and provide enough airflow, but no luck.

Any car-smart people want to chime in? We'll take it back to the mechanic again when it gets home from this trip, but it would be nice if I could make a few suggestions on things for him to look for.

 

[DEEKAYPEE8569]

We have a 2009 Vue with an intermittent A/C problem that has been hard to figure out. Thought I'd run it past you guys and see if anyone had an idea.

The air conditioner functions perfectly during everyday, around town driving. In fact, it's ice cold, very nice. But if you take the vehicle on a longer trip, more than about 2 hours, it shuts off. Basically, it's icing over, except it's not actually icing over - it shuts off automatically when the condenser (or whatever part of the a/c actually gets cold, I could be using the wrong terminology) gets below a certain temp. The blower fan is still moving air, but the compressor has been turned off, so the air the blower is moving is hot air.

If you turn off the a/c and let things warm back up, then it will turn on and function perfectly again, until the cycle repeats.

I've taken it to a mechanic, he hooked up diagnostics to the a/c and reported everything functioning a-ok. No freon leak, nothing unexpected. At the time, we discovered that I have a cabin air filter that was filthy, so we figured the a/c wasn't getting enough airflow and that's why it was getting too cold.

The cabin filter was just replaced about a month ago, so it shouldn't be due for replacement yet, but we are running into the same problem on a long trip right now. We've tried running it only on recirculate, hoping that would bypass the cabin filter and provide enough airflow, but no luck.

Any car-smart people want to chime in? We'll take it back to the mechanic again when it gets home from this trip, but it would be nice if I could make a few suggestions on things for him to look for.

It could be a heater core problem. Yes, it sounds counter-intuitive to mention a heater core, but if they get plugged up with crud, it can cause A/C malfunction. The heater core stores hot coolant for use, but it also serves as a cooling unit, as does the radiator. Another possibility; you may need a new thermostat. Is your water temp. within normal parameters; ie; 212 deg or below? OR.....you may just need to recharge the system with the appropriate refrigerant. Most cars now use R-134A, as R-12 is not used in passenger cars anymore. Check to see which your Saturn uses; prob'ly R134A; and try recharging the system. It sounds like you have a freon leak; at best, you don't; you just need to recharge the system. If you decide to tackle the task yourself, just be sure not to mix up the high pressure side with the low pressure side.
Also, if you only get the can of freon and the recharge hose, keep the can upright; don't shake it or turn it upside down once it's hooked up. Rightside up refills liquid freon. Upside down refills freon in gaseous form.

 

[MadDogMarine]

Tough to troubleshoot! Obtaining a wiring diagram for the A/C control would probably help a lot.

A few suggestions from here
Mercedes-Benz A/C Control Diagnostics
"The greatest challenge to a diagnostic technician comes from the intermittent problems involved with the compressor control system. This system, once used only for evaporator temperature control and low refrigerant compressor protection, is now used for multiple protection, efficiency and engine power considerations. The compressor can be disengaged to protect the belt system and the engine temperature, and possibly even the electrical system from low voltage and the idle from going too low. It is disengaged to control evaporator temperature and is engaged to dehumidify the windows in defrost no matter where the temperature is set. The compressor is disengaged on diesels to give more power in full throttle."

 

[Merlin99]

We have a 2009 Vue with an intermittent A/C problem that has been hard to figure out. Thought I'd run it past you guys and see if anyone had an idea.

The air conditioner functions perfectly during everyday, around town driving. In fact, it's ice cold, very nice. But if you take the vehicle on a longer trip, more than about 2 hours, it shuts off. Basically, it's icing over, except it's not actually icing over - it shuts off automatically when the condenser (or whatever part of the a/c actually gets cold, I could be using the wrong terminology) gets below a certain temp. The blower fan is still moving air, but the compressor has been turned off, so the air the blower is moving is hot air.

If you turn off the a/c and let things warm back up, then it will turn on and function perfectly again, until the cycle repeats.

I've taken it to a mechanic, he hooked up diagnostics to the a/c and reported everything functioning a-ok. No freon leak, nothing unexpected. At the time, we discovered that I have a cabin air filter that was filthy, so we figured the a/c wasn't getting enough airflow and that's why it was getting too cold.

The cabin filter was just replaced about a month ago, so it shouldn't be due for replacement yet, but we are running into the same problem on a long trip right now. We've tried running it only on recirculate, hoping that would bypass the cabin filter and provide enough airflow, but no luck.

Any car-smart people want to chime in? We'll take it back to the mechanic again when it gets home from this trip, but it would be nice if I could make a few suggestions on things for him to look for.

Overcharged freon will do this.

 

[bohman]

It could be a heater core problem. Yes, it sounds counter-intuitive to mention a heater core, but if they get plugged up with crud, it can cause A/C malfunction. The heater core stores hot coolant for use, but it also serves as a cooling unit, as does the radiator. Another possibility; you may need a new thermostat. Is your water temp. within normal parameters; ie; 212 deg or below? OR.....you may just need to recharge the system with the appropriate refrigerant. Most cars now use R-134A, as R-12 is not used in passenger cars anymore. Check to see which your Saturn uses; prob'ly R134A; and try recharging the system. It sounds like you have a freon leak; at best, you don't; you just need to recharge the system. If you decide to tackle the task yourself, just be sure not to mix up the high pressure side with the low pressure side.
Also, if you only get the can of freon and the recharge hose, keep the can upright; don't shake it or turn it upside down once it's hooked up. Rightside up refills liquid freon. Upside down refills freon in gaseous form.

Not quite sure I understand how the heater core would affect my air conditioner compressor? Should some heat from the core be sent to the condensor? The problem, as far as I know, is the condenser getting too cold and the system shuts off automatically.

It's definitely not a freon leak, the system was fully charged. As for water temp, it maintains a steady temp between 190 and 195. No trouble there as far as I can tell. But that doesn't mean water is flowing through the core properly, either.

Tough to troubleshoot! Obtaining a wiring diagram for the A/C control would probably help a lot.

A few suggestions from here
Mercedes-Benz A/C Control Diagnostics
"The greatest challenge to a diagnostic technician comes from the intermittent problems involved with the compressor control system. This system, once used only for evaporator temperature control and low refrigerant compressor protection, is now used for multiple protection, efficiency and engine power considerations. The compressor can be disengaged to protect the belt system and the engine temperature, and possibly even the electrical system from low voltage and the idle from going too low. It is disengaged to control evaporator temperature and is engaged to dehumidify the windows in defrost no matter where the temperature is set. The compressor is disengaged on diesels to give more power in full throttle."

Interesting info there. I'm not sure it helps me, since most of it related to problems at low or unsteady RPMs - my problem is happening during long highway drives, so no low RPM situations involved.

Overcharged freon will do this.

My mechanic did say the system was full, maybe it was too much? He just said it was within expected limits.

Thanks for all the reponses, keep 'em coming!

 

[MadDogMarine]

My mechanic did say the system was full, maybe it was too much? He just said it was within expected limits.

Thanks for all the reponses, keep 'em coming!

Sorry, looks like the Vue has a history of bad A/C + high repair costs.Saturn VUE AC and Heat Problems - Car Forums - Edmunds

One possible simple solution
:Our 2009 VUE air conditioner would blow warm after driving for an hour or 2. Since the dealership we use (only certified Saturn repair shop since Saturn went under) is always busy, I asked the service writer if he would like us to replicate the problem and bring it in when it started acting up. He agreed and we were able to show up with the problem replicated and they could see what was happening.
When the air conditioner would blow warm, there would be a connection behind the engine that would ice over (the longer it ran, the bigger the chunk of ice). If you follow the metal lines from the A/C compressor towards the back of the engine, you will see the connection.
Within an hour, the service writer came back and told us it was the expansion valve. Our air conditioner has been working fine since.
I suggest, if you can, replicate the problem and drive to the repair shop while the problem is happening. Don't even turn the car off until they can see it.
I know there are shady mechanics out there, but, from what I've seen, most mechanics want to fix your car and it is frustrating for them when they can't duplicate your problem. I hope this helps. "

Proper A/C service would include vacating the existing freon. Draw a vacuum, weigh and recharge with the exact amount per manuf. specs which is rarely done with a lot of these shops.

 

[Chris0nllyn]

My guess is that the compressor clutch coil is heating up after so long, and is no longer able to hold the plate.

 

[bohman]

Sorry, looks like the Vue has a history of bad A/C + high repair costs.Saturn VUE AC and Heat Problems - Car Forums - Edmunds

One possible simple solution
:Our 2009 VUE air conditioner would blow warm after driving for an hour or 2. Since the dealership we use (only certified Saturn repair shop since Saturn went under) is always busy, I asked the service writer if he would like us to replicate the problem and bring it in when it started acting up. He agreed and we were able to show up with the problem replicated and they could see what was happening.
When the air conditioner would blow warm, there would be a connection behind the engine that would ice over (the longer it ran, the bigger the chunk of ice). If you follow the metal lines from the A/C compressor towards the back of the engine, you will see the connection.
Within an hour, the service writer came back and told us it was the expansion valve. Our air conditioner has been working fine since.
I suggest, if you can, replicate the problem and drive to the repair shop while the problem is happening. Don't even turn the car off until they can see it.
I know there are shady mechanics out there, but, from what I've seen, most mechanics want to fix your car and it is frustrating for them when they can't duplicate your problem. I hope this helps. "

Proper A/C service would include vacating the existing freon. Draw a vacuum, weigh and recharge with the exact amount per manuf. specs which is rarely done with a lot of these shops.

Hmmm. Not exactly what you want to see, but thank you. Lots of info there.

My guess is that the compressor clutch coil is heating up after so long, and is no longer able to hold the plate.

Sounds like a reasonable guess, I wonder if that's something that mechanic can check without running up a massive labor bill?

 

[Chris0nllyn]

Sounds like a reasonable guess, I wonder if that's something that mechanic can check without running up a massive labor bill?

I would let it idle with the a/c on for awhile, then rev the engine, or accelerate quickly after the clutch on the compressor has been heatsoaked.

Do you notice it turn off after coming from a red light? Does it stay on when at cruising speed?

Some compressors actually have shims that can be removed, but I'm not sure about the Vue.

 

[struggler44]

Does the fan position have any effect on this? Does running the fan on high prolong the inevitable freeze up?


Do you get plenty of condensate water under the vehicle?

 

[struggler44]

I would let it idle with the a/c on for awhile, then rev the engine, or accelerate quickly after the clutch on the compressor has been heatsoaked.

Do you notice it turn off after coming from a red light? Does it stay on when at cruising speed?

Some compressors actually have shims that can be removed, but I'm not sure about the Vue.

It's freezing up so my guess would be the clutch is staying engaged....

 

[Chris0nllyn]

It's freezing up so my guess would be the clutch is staying engaged....

I highly doubt it's freezing up.

If the clutch stayed engaged, the compressor would run, and cold air would blow.

Freezing of any a/c system doesn't happen at the compressor, but at the evaporator (which is typically enclosed, either inside the dash, or right outside of it). Low air flow or low freon means the evaporator coil cannot operate to properly dissipate heat, and in effect 'overcools' itself. Condensation happens, and eventually ice.

 

[struggler44]

I highly doubt it's freezing up.

If the clutch stayed engaged, the compressor would run, and cold air would blow.

Freezing of any a/c system doesn't happen at the compressor, but at the evaporator (which is typically enclosed, either inside the dash, or right outside of it). Low air flow or low freon means the evaporator coil cannot operate to properly dissipate heat, and in effect 'overcools' itself. Condensation happens, and eventually ice.

Correct, unless it freezes up, the LP switch should stop this from happening, .... 130 will not stop it from freezing if that's what the problem is, I re-read the post and seen where he/she didn't say it was freezing over. Freezing can take place anywhere in the system if the TXV is flooding, actually where ever moisture comes in contact with the sub-zero surface but most of the time starts at the evap because that's the closest point to where the txv is located and works it way back towards the compressor ..... maybe the LP switch is not breaking as designed?

 

[Chris0nllyn]

Correct, unless it freezes up, the LP switch should stop this from happening, .... 130 will not stop it from freezing if that's what the problem is, I re-read the post and seen where he/she didn't say it was freezing over. Freezing can take place anywhere in the system if the TXV is flooding, actually where ever moisture comes in contact with the sub-zero surface but most of the time starts at the evap because that's the closest point to where the txv is located and works it way back towards the compressor ..... maybe the LP switch is not breaking as designed?

The LP, HP, and freeze switches are all in series. They all do one thing, cut power to the compressor. OP, make a jumper out of a paperclip, and bypass each one.

LP switch is only going to open when there isn't any freon. HP switch is the opposite, and a bad freeze switch would cause the evaporator to freeze up. You'd see water pouring out of the evap drain tube when it melts.

 

[struggler44]

The LP, HP, and freeze switches are all in series. They all do one thing, cut power to the compressor. OP, make a jumper out of a paperclip, and bypass each one.

LP switch is only going to open when there isn't any freon. HP switch is the opposite, and a bad freeze switch would cause the evaporator to freeze up. You'd see water pouring out of the evap drain tube when it melts.

The compressor on a vehicle cycles on the LP switch, that's why you hear the compressor start and stop at low RPM ....... No, I'm not a car mechanic, lol

 

[Chris0nllyn]

The compressor on a vehicle cycles on the LP switch, that's why you hear the compressor start and stop at low RPM ....... No, I'm not a car mechanic, lol

Neither am I

Just picked up info from my dad over the years. He's been a mechanic for 30+ years.

My a/c comp cycles at any RPM....you're right though, the pressure switches and/or freeze switch turn the comp on/off.

 

[bohman]

I would let it idle with the a/c on for awhile, then rev the engine, or accelerate quickly after the clutch on the compressor has been heatsoaked.

Do you notice it turn off after coming from a red light? Does it stay on when at cruising speed?

Some compressors actually have shims that can be removed, but I'm not sure about the Vue.

The problem is only occurring on long trips, at steady cruising speeds (50mph +) The a/c has never shut down on a trip less than an hour, which is why the problem has been hard to diagnose. It almost never happens.

Does the fan position have any effect on this? Does running the fan on high prolong the inevitable freeze up?


Do you get plenty of condensate water under the vehicle?

Fan position had no effect. Switch from fresh air to recirc had no effect either. I had read that the cabin air filter was only in effect when using fresh air, so I had hoped that keeping it on recirc would provide enough air flow to keep it from getting too cold, but no luck.

Plenty of water draining out, no blockage there.

Correct, unless it freezes up, the LP switch should stop this from happening, .... 130 will not stop it from freezing if that's what the problem is, I re-read the post and seen where he/she didn't say it was freezing over. Freezing can take place anywhere in the system if the TXV is flooding, actually where ever moisture comes in contact with the sub-zero surface but most of the time starts at the evap because that's the closest point to where the txv is located and works it way back towards the compressor ..... maybe the LP switch is not breaking as designed?

The LP, HP, and freeze switches are all in series. They all do one thing, cut power to the compressor. OP, make a jumper out of a paperclip, and bypass each one.

LP switch is only going to open when there isn't any freon. HP switch is the opposite, and a bad freeze switch would cause the evaporator to freeze up. You'd see water pouring out of the evap drain tube when it melts.

What my mechanic told me when this happened last summer is that the evap never actually froze up - the system monitors temperature and shuts off just before it gets to point of freezing. So you shouldn't ever see the block of ice and then eventual melting (a process which I am familiar with thanks to a crappy apartment heat pump), the system automatically cuts off before that happens.

The question is, why is it getting cold enough to shut off? We thought we found the solution when we realized that we have a cabin air filter that needs to be kept clean, but that didn't help us this time. I appreciate the input, and I'll keep you guys posted when we have a chance to take the car into the shop again.

 

[struggler44]

The problem is only occurring on long trips, at steady cruising speeds (50mph +) The a/c has never shut down on a trip less than an hour, which is why the problem has been hard to diagnose. It almost never happens.



Fan position had no effect. Switch from fresh air to recirc had no effect either. I had read that the cabin air filter was only in effect when using fresh air, so I had hoped that keeping it on recirc would provide enough air flow to keep it from getting too cold, but no luck.

Plenty of water draining out, no blockage there.





What my mechanic told me when this happened last summer is that the evap never actually froze up - the system monitors temperature and shuts off just before it gets to point of freezing. So you shouldn't ever see the block of ice and then eventual melting (a process which I am familiar with thanks to a crappy apartment heat pump), the system automatically cuts off before that happens.

The question is, why is it getting cold enough to shut off? We thought we found the solution when we realized that we have a cabin air filter that needs to be kept clean, but that didn't help us this time. I appreciate the input, and I'll keep you guys posted when we have a chance to take the car into the shop again.

Good luck ....

 

[bohman]

Good luck ....

Thanks. With a problem this hard to replicate, I'll need it.

Just as an update - when the car arrived home this week (Jacksonville to SOMD in a day) the a/c was non-functional. Parked the car and unpacked. Two hours later, I noticed that the a/c drain tube was STILL dripping water. Not just a drop or two, but a steady drip.

When we had this problem last year, it was my understanding that the evaporator wasn't actually freezing over - the system shut off before it got to that point. But draining water for 2 hours tells me that there must have been a good chunk of ice in there, and it took that long for all of it to melt.

 

[Dead Eye]

Lot of things it could be. You need a professional refrigerant technician to find it. Off top of my head could be moisture turning to ice inside the expansion device. (ever had system open before~ie replace a part?).

Take it to Redgate Auto Air.