Air Conditioner/Heater work sporadically

rha

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2011 Regal
We are at our wit's end. Our Regal's AC/Heater unit sometimes works, sometimes doesn't. A GM dealer couldn't fix it, nor an independed mechanic with a superb reputation. No leak, compressor ok, seems to have something to do with something else. Is there a thread about such concerns?
 

MelsRegal

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Regal GS 2017
what exactly do you mean by the AC/Heater unit sometimes works, you mean no air flow comes out of any of the vents, the air flows out of only some of the vents, the air isnt hot when it should be, the air isnt cold when it should be, etc.? Did the dealer or the mechanic replace any parts? Need more information about the problem and what has already been attempted.
 

rha

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2011 Regal
what exactly do you mean by the AC/Heater unit sometimes works, you mean no air flow comes out of any of the vents, the air flows out of only some of the vents, the air isnt hot when it should be, the air isnt cold when it should be, etc.? Did the dealer or the mechanic replace any parts? Need more information about the problem and what has already been attempted.
Thanks for responding so quickly and sorry about the vague message. What was happening was and is this. At start up in the morning, we got some air conditioning but it would periodically turn on and off (the cooling, not the fan and vents), but the worst was when we started up the car after it sat in a parking lots for an hour, it would take as much as 15 minutes to begin to give us lukewarm and not hot air (we are in Texas, so the challenge is great). And then it would shut down. It almost feels like a thermostat kind of problem but no one has mentioned the existence of a thermostat for this system. When we took it to the dealerships, the mechanics there tested the compressor (fine), replaced the high and low service valves. They suspected that the schrader valves were leaking. Still no luck. There also was much coolant present and no obvious leak. We were charged for the parts of labor that didn't work and were quoted upward of $2000 more work needed, but with no guarantee that this would solve the problem. Furthermore, when we looked at the engine compartment after we said we had to think about this, it was a mess, with even the caps on the valve new valve parts missing. We got them to clean it all up, but that alone was not a vote of confidence for the mechanics.
We then took it to an independent mechanic, who found no leaks, no problem with the compressor, and this same problem of the AC going on for a bit and then quitting, the vents still blowing but now hot air. Very frustrating.
 

pigsnzen

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BFE, KY
Buick Ownership
'12 GS 6MT
I wonder if the A/C compressor clutch/sensor is on it's last legs? Sometimes a bad temp sensor (that drives the A/C clutch actuation) will cause similar symptoms - at least it did on my wife's Fusion.
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rha

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2011 Regal
Thanks. Worth checking out and no one has mentioned anything like it.
 

2007LucerneCXL

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2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
For others what year and type of HVAC control unit. Is the outside air temp display correct? As it appears that the dealer was trouble shooting by parts and not necessarily identified the root cause if it's not mechanical then it's electronics. Unfortunately it may not be a single answer, but if all the AC components are good and it's blowing cold air at times it could be in the A/C Heater blend door actuators or the control panel but its unknown if this had been checked.
 

rha

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2011 Regal
My wife reminded me of the following, which was on a webposting but which neither the dealer nor the independent mechanic could follow. Perhaps one of you out there can make sense of it for a first step out of the predicament we find ourselves in:
The problem was solved by checking the car in morning when the air worked great when things were at lower temperatures outside between 70-80 degrees. Wife drive to work comes out in afternoon at 4:30pm around 100 plus degrees constantly around here in central calif. Turn air on and it comes on blowing hot air right away, and it stays hot after 10 minutes or so and no work. When and if it does work at all, if lucky in a spurt, manual or auto makes no difference, it works pretty good for a few minutes but still seems like it's not as cold as during last year in the hot days, then it shuts down to hot air rest of drive home from work. Another note here: when the cars AC stopped blowing cold air I would stop car leave it running and you could see the AC compressor still turning so the compressor is not being turned off by anything that'* a good sign.

Week end rolls around get up in morning (8:00 am) take care to an old time mechanic racing car friend and we check the AC pressure both low and High side with engine off not running. All is right in specs for car. We check the car when running all is in specs.

I drive the car for a bit it works for a round trip of 20 miles then back home park car outside in the sun. I wait till afternoon Now its 2:00 pm afternoon...outside temp is at 103 degrees. Get in car inside hotter than hell since my car is jet black paint and jet black interior it does keep it hot in and out side on hot days. Start car air on, tried manual and auto, and it blows nothing but hot air for five minutes check compressor, it’s on and turning fine but no cold air, no weird noises all appears normal.

Now drive car to friend again he hooks stuff and gauges etc again. He check the AC low and high side again while running and while engine off. He finds there's an imbalance between the low and high side when running that's out of car specs. It’s not much but enough to cause the car not to have cold air come out the Evaporator side into the cars vents. It just stays hot air period.

He set the balance for low and high side pressures, naturally while engine running, keeping with in specs till it started working great. Cold air flowed best ever like new again. Once he found its happy place he checked specs we were still in specs but showed it was balanced and all was working well. I drove the car to a local store to buy some stuff that was 60 mile round trip. All worked great matter of fact I set the auto to 72 degrees and it kept it there great. The car now gets cold so that you don't want to set too low of an inside temp but the auto and manual work like the day I bought the car over two years ago.


So be advised your car may need some TLC after its gets a few miles doesn't mean it's bad just need some TLC in some of its setting at times. I had to many dealers that couldn't get the problem to happen or didn't spend the time like I did to see the problem and No leaks of the AC system. Its been checked by dealer and others more than once. Car has 84,125 miles now on it wife's driven car to and from work for a few weeks now still temps in the 100 to 108 in afternoons around here and the car has not failed to provide cold air even once in all that time.

Now one would have thought the dealers should have caught this yet then again no codes were thrown in the AC computer modules or any of the cars systems for that matter. But the dealers were looking at it and taking a hammer, and to them, all problem looked like a nail, it seemed to me.

Anyway I wasn't going to get into the technical stuff with my race car friend who tears this stuff down with his eyes closed, I just wanted to get it fixed using some old time common things approach and some logical thinking to it and now its fixed. I have so many dealers and non-owners of this type car say that couldn't have fixed it. Where and how many times have I and others heard such things before.

The cars today have some logic from yesterday yet they do have lots of added parts just to control something like air conditioning. Sometimes what works in the "box" will be something working outside the "box". That's life my friends and the way of our cars today as well as yesterday. I know one thing, I know where and what every part is and does on my car now in the Air Condition system. HVAC Module and BCM are just some key players for a start.

And it all turns out to be a little pressure problem with temps. I won't forget this one that's for sure. Well, I hope this helps someone else, seems after I had my problem I ran into some other Buick owners of newer cars with a like problem and so far they did the check of Compressor the way I did and have all had the same fix done and fixed there problems as well. Seems this is a problem among more than a few Buick owners I ran across in other places now.
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Dewayne5

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Buck Regal CXL 6MT Active
Check the ambient temperature sensor. Usually cost 20 to 25 dollar. Was a real problem on a sister car. The saab 9³.
 

2007LucerneCXL

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2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Thanks for sharing the details and write up. Glad you had the person who can think with there head and not there keyboard as its getting harder each year to find them.
 
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