AC issues

Cape Cod GN

Member
Joined
May 21, 2014
Hello everyone. I’m having issues with the AC clutch engaging on a 134 converted system.
Here’s what’s I’ve checked:
- I jumped the low side with a paper clip and the clutch engages.
- I checked the ECM SOL 10 amp fuze as well as replaced the AC compressor control relay.
- Low side pressure is at 38 psi.
I also replaced the high side switch which was leaking a bit.
- There maybe a slow leak in one of the lines.
Question is what should the low side pressure read (I’m using a bottle to refill) and at what psi will the clutch kick on?
Thank you, any help or ideas would be appreciated.
 

regan j

Active Member
Joined
Sep 19, 2008
Hi and Low sides will equalize when clutch is not engaged with engine running so I suspect you are low on your charge. Depending on outside temps, you should see close to 100 psi on low side when equalized and a running pressure of about 40 when engaged.
 

salvageV6

Daily Driver
Joined
May 25, 2001
The low side switch closes at approx. 25 psi. per the service manual, so if you jump it and everything works properly with the paper clip, and the low side pressure is 38 psi. you have a bad switch.
 

Chuck Leeper

Toxic old bastard
Staff member
Joined
May 28, 2001
That’s the plan...however I do not know where the leak is or how bad. I want to get the system working and charged then use the UV light once I know it is running.
Add a can of freon with UV dye in it. 1 can should be enough the allow the compressor to start.
Check w/ the black lite.
Being the dye is fluorescent green, you can probably see it with the naked eye.
Original hoses tend to seep thru the liner w/ 134. Also, if they are originals, just moving them can/will cause leaks.
 

Cape Cod GN

Member
Joined
May 21, 2014
The low side switch closes at approx. 25 psi. per the service manual, so if you jump it and everything works properly with the paper clip, and the low side pressure is 38 psi. you have a bad switch.
Thanks Salvage. This morning I added more R134 and the clutch engages for 2 seconds then shuts off for about 8 seconds then kicks on again for 2 sec in a pattern. Any ideas? Could it still be a switch or maybe a ground? Thanks.
 

salvageV6

Daily Driver
Joined
May 25, 2001
Sounds like a charge issue, if you are using gauges which you should be, what do they read at the low side when cycling on/off?
 

Cape Cod GN

Member
Joined
May 21, 2014
When the compressor kicks on for that 2 seconds it drop to about 15 psi.
I see no fresh leaks with my UV light.
 
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