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Discussion Starter · #1 ·
My headunit 09 g8 gt stock. Was blacking out. When that happens. The a/c kicks on full blast through front defrost. Was pulling hvac an blower fuse under hood to shut off. Went to florida put fuses back in. Better then nothing. A/c started blowing hot. Fixed radio was the fuse on back of headunit. Then ac was blowing hot. Freon Charge is good. When bleeding low pressure the freon was hot. Had system vacuumed and replaced freon but high sode would go to about 100 and drop. Read all the forums. And didn’t want to just throw. Condenser, compressor and receiver/dryer at it. Please help someone summer with no a/c sucks. Want to self diagnose . But might have to give an ac tech the $$$
 

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Man, that's a nasty problem you got there. If you know that the fuses pulled were still good, an were reinstalled in there correct locations, I'm stumped for now (or forever). For sure, your compressor belt is still routed under its tensioner pulley as required, in order to spin the compressor ? I'm not sure what the HVAC would act like, if the compressor belt lost its tension an could no longer rotate it.
 

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Discussion Starter · #3 ·
The 2 fuses i pulled to shut off hvac under hood are both new and in correct location. The belt is routed correctly and has tension. Fuse in radio was replaced and unit works. I have no idea. Been reading every a/c post here. And i see two options. Throw parts or bring to ac tech and he’ll probably say the same
 

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Was your A/C system working correctly prior to your radio/hvac multi function face plate randomly shutting down ? Can you turn on an off the A/C system, an get the appropriate info displayed in your multi function display (even if you are unable to get any cold air) ? Are you able to select all of the 20 fan speeds when using that fan rocker switch ? If the high side pressure reading never exceedscv100 psi, it sounds like your either out of refrigerant, or the compressor is not responding to the signal sent to it from the hvac controller, to compress more refrigerant to make lots of cold air.

They show a system reset procedure that would be required "if" the controller or an actuator had been replaced. It says (with ignition off) to pull that HVAC/BATT fuse (as you did before) for 30 seconds or more, then reinstall. Start the engine an "do not" mess with any of the hvac controls for at least 60 seconds. This allows the hvac system to re-calibrate itself. Very small chance this will help, but easy to do. They say if somehow the hvac system found a way to"get out" of calibration, the temp control would get all messed up
 

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Agree - try the battery removal / system reset.

I would also confirm the fuses were seated properly and have not blown.

Does the compressor cycle at all?
 

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Discussion Starter · #6 ·
Was your A/C system working correctly prior to your radio/hvac multi function face plate randomly shutting down ? Can you turn on an off the A/C system, an get the appropriate info displayed in your multi function display (even if you are unable to get any cold air) ? Are you able to select all of the 20 fan speeds when using that fan rocker switch ? If the high side pressure reading never exceedscv100 psi, it sounds like your either out of refrigerant, or the compressor is not responding to the signal sent to it from the hvac controller, to compress more refrigerant to make lots of cold air.

They show a system reset procedure that would be required "if" the controller or an actuator had been replaced. It says (with ignition off) to pull that HVAC/BATT fuse (as you did before) for 30 seconds or more, then reinstall. Start the engine an "do not" mess with any of the hvac controls for at least 60 seconds. This allows the hvac system to re-calibrate itself. Very small chance this will help, but easy to do. They say if somehow the hvac system found a way to"get out" of calibration, the temp control would get all messed up
 

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Discussion Starter · #7 ·
Tes i can cycle through all 20 fan speeds and turn a/c on and off. I tried to pulling the fuses like you said with no change. I will try again. So AC worked prior to faceplate shutting off and found fix was fuse blown on rear of receiver on passenger side of radio. When the faceplate went out. The default is for a/c to come on full blast through the front defroster. First time radio kicked off was still cold in New England so i just pulled fuses for hvac/blwr 40a under hood fu-9 and f37-10a hvac ign. Then drove to florida soon after and figured ac through defrost was better then nothing. So plugged fuses back in. Then a couple days later noticed ac was no longer cold through defrost.
 

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Discussion Starter · #8 ·
Eventually got back home. Found blown fuse on rear of receiver and faceplate turned on. And ac not blowing cold. Brought to a friend and vaccuumed system. Put I believe 1 lb in system. All that would take because i guess compressor not engaging even though variable compressor etc.
 

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Discussion Starter · #9 ·
Agree - try the battery removal / system reset.

I would also confirm the fuses were seated properly and have not blown.

Does the compressor cycle at all?
i know they say its the variable compressor and always running but i dont feel it’s really engaging like it used to when i would have functional ac. Low side line is hot to. Probably normal considering no freon being pushed through the line
 

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Those that say the compressor runs all the time (including me), are correct. Because the compressors cold air output is sorta slaved in from minimum to maximum efficiency, you can not tell or hear the change the compressor output is making. Its a very slick functioning automatic system, when all of the system parts as well as having the correct amount of refrigerant within it, are working as they should.
If you can guess what you believe the underhood temp is (say after a couple of hours of sitting), both the low an high pressure lines should have the same general temp feel to them. If you had access to an A/C system pressure test set, you could hook it up, an expect to see a low an high psi reading of about 70 psi if the surrounding area is about 70 deg F.. If it feels like 80 deg F, the line pressure should read about 86 psi. If 100 deg F, the pressure would be about 124 psi. More later.

With a good system running, you could expect to see a low pressure reading around 30 to 45 psi and the high pressure like 180 to 250 psi


I know on somewhat warm/hot humid days, a good A/C system (after running full cold for about 10 minutes or more) you could expect to see the low pressure line loaded with very cold water beads or light frost. An the high pressure line so hot, one quick touch will remind you to not do that again.
 

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Discussion Starter · #11 ·
Sp is there no way to test a condenser or compressor. Like i stated before i know four seasons makes a tool for ecv variable compressors to manually test . But haven’t learned enough about to go there. Honestly feel if i bring to an ac tech they will most likely try to over chrge and throw parts at with absurd labor included. Seems to me it can only be what a Condenser, Receiver/Drier Or Compressor or possibly computer problem?
 

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There are shops that solve A/C systems along with other auto problems, as well as shops that "only" solve A/C problems. When they test the A/C system, they are able to tell you what component(s) is or has failed biased on the low an high psi readings the car produces. Having done this to a huge number of vehicles over time, I think they are very good at advising you what the psi numbers indicate as to what's wrong. Some will charge very little (if anything) to run a psi system test.

If the A/C system pressure sensor were to fail high or low (even with the correct amount of refridgerent in the system), that compressor will "not" start making cold air. If the pulsed voltage compressor slaving clutch is "stuck" at the minimum psi request position (which equals OFF), no cold air will be created. If the compressors shaft has sheared within, no cold air will be forthcoming. If you choose to due nothing (which is what it reads like), it looks like zero cold for the remainder of your ownership.
 

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Discussion Starter · #13 ·
Yes originally abput a week and a half ago. I had an acquaintance vaccum the system and charge half way due to the compressor not fully opening and allowing the full amount. He hooked gauges up and said the high side jumped to anout 100 psi then dropped back down. I should probably find a shop but am stubborn and love to diy myself and learn. But stubborn vs heat. The heat may win
 

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Discussion Starter · #14 ·
I replaced the high pressure ac sensor. And tried the 30 sec reset pulling the fuse as gopherit stated. Tge low pressure line now gets cold as it should. The air coming out of the vents isn’t hot anymore but not cold. Now trying to figure out next step
 

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Discussion Starter · #15 ·
Nevermind. Realized low pressure line was cold after i added a small amount of freon. Have a mechanic appointment tomorrow
 

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Discussion Starter · #16 ·
So I brought it to a shop and they said i was getting 5 volts sent to compressor when demanded to kick on and they leak tested etc. said it was most likely the compressor and need to be replaced. Im going to order compressor , expansion valve and condenser kit w all o rings. Will most likely use a month of all data to find tear down and replacement procedure for compressor. Seems straightforward but just in case. Basically I’ve come to the conclusion. They’re is 3 fuses that run the hvac. The hbac blower 40amp the hbac ignition 10amp and hbac battery 10amp. When my radio shut off and ac came on defrost . I pulled the blower and ignition fuse amd left battery fuse in and belt on compressor. So possibly doing that without removing battery fuse led to an overload or failure? Idk but that’s where im at
 

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Discussion Starter · #17 ·
So I replaced the Compressor condenser receiver and dryer and expansion valve thanks to the help of another board members right up on replacing all AC components wasn’t very difficult to deal just difficult getting to the bolts for the compressor and hose clamps for power steering cooler also replaced high side pressure switch on back of compressor had it vacuumed and recharged the temperature to the van was 59°F I have heard of it beingcooler than that I heard the evaporator core could get full of dirt and dust debris and cause it from being colder but I am fine with 59°
 
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