A/C Intermittently Working (1 Viewer)

Joined
Mar 7, 2020
Messages
6
Location
Florida
Before I go too far, if this is already documented somewhere I'd appreciate a link. Did some searching on the forum but only found spread out posts.

I'm starting to have issues with my A/C intermittently working. When hitting the A/C button I can hear the relay in the glovebox click over and the clutch engage and idle goes up for .5 second. Sometimes it works perfectly fine and the A/C kicks on / off and blows cold no problem. But sometimes it will not kick on period. Funny enough if i just hold down the A/C button it will kick on and work no problem. Long story short, if and when the clutch engages and it idles up it will blow cold. Why it will sometimes not even kick in is what has me stumped.

I live in North East FL. The highest temp we have hit so far this year is 78 degrees F.

Where would you start?

Thanks.
 

voodu3

SILVER Star
Joined
Oct 13, 2017
Messages
984
Location
Signal Mountain,TN
It sounds like your switch in the dash is bad or going bad. I think there is a spring in that wears out. Search ac switch replacement you should get some good results. Good luck. Florida with no ac doesn’t sound like fun.
 
Joined
May 3, 2016
Messages
1,039
Location
odessa, tx
Mine used to kick on and off at idle and I could hear a relay clicking on and off under the dash. It was annoying and often the AC would cut out in the heat. Replacing the radiator got my engine temps down which made it stop cutting out completely. however it continued to kick on and off at idle. when I rebuilt my engine I replaced the compressor and recharged the system and now it doesn't click on and off at idle. Long story short the ac will cut off if the engine temp is too high or if the system isn't properly charged. If you over charge it the pressure get to high on the high end and low end and will cut on and off. I would recommend charging it correctly with gauges as a good first start. PO may have overcharged the system.
 
Joined
Mar 7, 2020
Messages
6
Location
Florida
Well back to the heat. My issue seemed to have gone away for a bit there but now it is back acting up again. I had the system drained and recharged to proper levels. Funny enough it was not overfilled but if anything a bit low. After a recharge, i'm left with the same issue. However, no leaks which i'm happy about.

I'm back to thinking it is the A/C button itself as simply pressing it you can hear the relay kick in/out more than once. If I get it in just the right spot everything works as expected. Luckily I have a spare unit to swap it out with to see if that is indeed the issue. I have tested this at both low / high engine temperatures. Max engine temp never went over 190f.

Once I get this sorted, I will be investing in a new blue clutch fan just for good measure.

Appreciate the feedback and will keep everyone posted.
 
Joined
Oct 12, 2010
Messages
170
Location
Colorado
MY '94 needed a new expansion valve when I had similar issues. It would blow cold for a while, then go warm. Make sure that when it's blowing warm that the compressor clutch is engaging. If it's blowing warm, the temp switch is in good order, charge is correct, and the clutch engages when you hit the AC switch, you probably need an expansion valve. The kit with a drier, o-rings, and expansion valve is not very expensive. I think I did the Rock Auto kit for $30, and another ~$90 to have the local shop refill.
 
Joined
Mar 7, 2020
Messages
6
Location
Florida
MY '94 needed a new expansion valve when I had similar issues. It would blow cold for a while, then go warm. Make sure that when it's blowing warm that the compressor clutch is engaging. If it's blowing warm, the temp switch is in good order, charge is correct, and the clutch engages when you hit the AC switch, you probably need an expansion valve. The kit with a drier, o-rings, and expansion valve is not very expensive. I think I did the Rock Auto kit for $30, and another ~$90 to have the local shop refill.

Thanks for the feedback. I have confirmed that when it's blowing warm the compressor is not engaging. I can hear the relay click in and out and when the compressor engages. I walk around to the front to validate that it is engaged and spinning. As long as I can get the button and relay to engage it will blow cold.

Should have the spare control unit in this weekend to test it further. If it's not the button fingers crossed it is not the A/C amplifier. Other than that I suppose the temp cut switch could be bad.

Cheers.
 
Joined
Mar 7, 2020
Messages
6
Location
Florida
Well back to the heat. My issue seemed to have gone away for a bit there but now it is back acting up again. I had the system drained and recharged to proper levels. Funny enough it was not overfilled but if anything a bit low. After a recharge, i'm left with the same issue. However, no leaks which i'm happy about.

I'm back to thinking it is the A/C button itself as simply pressing it you can hear the relay kick in/out more than once. If I get it in just the right spot everything works as expected. Luckily I have a spare unit to swap it out with to see if that is indeed the issue. I have tested this at both low / high engine temperatures. Max engine temp never went over 190f.

Once I get this sorted, I will be investing in a new blue clutch fan just for good measure.

Appreciate the feedback and will keep everyone posted.
 
Joined
Mar 7, 2020
Messages
6
Location
Florida
Figured I would circle back and post my resolution. I took the car to an A/C shop and had them test drain and recharge the system. The pressure was not low or over filled. Also bought an OBD2 scanner so I could validate the engine temp. No overheating. After all this, I still had the same issue. I took the A/C amplifier out and visually inspected that. No issue there either. By this time the A/C only worked if I held the A/C button I’m the perfect spot.

My buddy had a spare A/C control unit that I finally was able to grab.Took the dash apart and popped the new one in and success, the A/C is working perfectly.

A decent sign you may have the same issue is if you can get the compressor to kick in while manipulating the button but it will not stay engaged. If I had to do it all again I would have tested the A/C amplifier as described in the FSM to pinpoint the exact issue faster. Hopefully this helps someone else.
 
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