AC and cooling fan issues... [Archive] - GrandAmGT.com Forum

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Starglow
07-16-2013, 05:57 AM
I have a question for those that have a non-working AC system. Does your cooling fans still run at high speed with the AC button pressed even if your compressor clutch does not engage?

I'm trying to debug the AC system on my GA. I know the high speed cooling fans work because I can jumper the relay to ground and make them run, but they do not turn on when I press the AC button. The system was low on Freon so I charged it and the compressor clutch engaged, but the fans still did not switch to high speed.

The compressor also would not dis-engage when I turned the AC button off, so the only way to dis-engage the compressor is to shut the blower fan off. The compressor also stays running all the time and never cycles.

I know there is a Freon leak, but I'm trying to understand when the fans should be running at high speed and if it's somehow pressure sensitive relative to the AC system charge.

The AC did blow cold air for a while even with the fans running on low speed but the Freon has leaked out again at this point. I have a sniffer device to help find the leak, but I'm at a loss as to why the fans are not switching speeds.

The PCM does have the Milzy tune, so I wonder if that is a contributing factor as well.

3800L67GAM
07-16-2013, 08:56 AM
I have a question for those that have a non-working AC system. Does your cooling fans still run at high speed with the AC button pressed even if your compressor clutch does not engage?

I'm trying to debug the AC system on my GA. I know the high speed cooling fans work because I can jumper the relay to ground and make them run, but they do not turn on when I press the AC button. The system was low on Freon so I charged it and the compressor clutch engaged, but the fans still did not switch to high speed.

The compressor also would not dis-engage when I turned the AC button off, so the only way to dis-engage the compressor is to shut the blower fan off. The compressor also stays running all the time and never cycles.

I know there is a Freon leak, but I'm trying to understand when the fans should be running at high speed and if it's somehow pressure sensitive relative to the AC system charge.

The AC did blow cold air for a while even with the fans running on low speed but the Freon has leaked out again at this point. I have a sniffer device to help find the leak, but I'm at a loss as to why the fans are not switching speeds.

The PCM does have the Milzy tune, so I wonder if that is a contributing factor as well.

Have you talked to mike about it yet I would've emailed him before posting to see what it could be just an idea!?!

bricooper78
07-16-2013, 09:04 AM
The blower fan has a relay that is kind of famous for failing, you'll lose speeds on your 1-5 switch, but usually you end up with 1 and 5, and that's it. Is that what isn't blowing?

Also, did you refill to the correct pressure? Too high is just as bad, if not worse than too low. I would wonder if that might be the problem for disengage... you could just be in need of a new compressor...lovely huh?

Starglow
07-16-2013, 09:21 AM
Have you talked to mike about it yet I would've emailed him before posting to see what it could be just an idea!?!

I talked to Mike about it some time ago and he didn't think the tune was at fault although he did change the temp set points when the fans turn on and off for cooling. The high speed fans have never worked since the tune.

Starglow
07-16-2013, 09:31 AM
The blower fan has a relay that is kind of famous for failing, you'll lose speeds on your 1-5 switch, but usually you end up with 1 and 5, and that's it. Is that what isn't blowing?

The blower fan works fine on all speeds, so no issues there. The engine cooling fans are the issue.


Also, did you refill to the correct pressure? Too high is just as bad, if not worse than too low. I would wonder if that might be the problem for disengage... you could just be in need of a new compressor...lovely huh?

I had a gauge set connected to both low and high pressure sides to monitor pressures. The AC worked for a while but again the compressor never cycles off & on and I know there's a yet to be found leak in the system.

I'm going to put some dye in it today to help locate the leak, but still scratching my head on the high speed fan issues.

bricooper78
07-16-2013, 04:35 PM
Back in the day on one of the berettas I had, the compressor starting "sticking" like that, and then I was coming back in town down the highway, and it started getting warm in the cab, I check the mirrors while driving, and looked up, and looked like a racecar that had barfed an engine lol huge trail of smoke behind me... stoopid compressor finally shredded the bearing, left metal bits all over, and the belt was spinning over top of the pulley. Aside of scaring the crap out of me, it didn't do too much damage since I was stopped within a mile, but I ended up "doing the Sleepy" and buying a shorter belt and bypassing that thing until I could afford it to be changed.
Then had a buddy with a suburban had one lock up on him, so I would guess you're on that beginning stage of a bearing failure/internal lockup and it's about to get worse, you might not want to buy more refrigerant until you change the compressor.

As for the coolant fans, I completely forgot they kick on with a/c lol