Search found 42 matches

by 71403
Wed Aug 22, 2018 10:46 am
Forum: Automotive Air Conditioning Forum
Topic: Resurrecting 1970 GM AC with POA
Replies: 17
Views: 546

Re: Resurrecting 1970 GM AC with POA

For anti-slug GM briefly pulses the compressor clutch during cranking.
by 71403
Tue Aug 21, 2018 2:36 pm
Forum: Automotive Air Conditioning Forum
Topic: Resurrecting 1970 GM AC with POA
Replies: 17
Views: 546

Re: Resurrecting 1970 GM AC with POA

Are you aware of a vacuum operated bypass valves that would be suitable? Four Seasons 74781, 5/8 and 3/4 hoses, apply vacuum to close. Stock app is 96-2000 GM trucks. Obviously you already know you can't use the PCM to run the compressor, because it needs the feedback from the 3 wire pressure senso...
by 71403
Mon Aug 20, 2018 6:23 pm
Forum: Automotive Air Conditioning Forum
Topic: Resurrecting 1970 GM AC with POA
Replies: 17
Views: 546

Re: Resurrecting 1970 GM AC with POA

Good plan, PF condenser and retain the TXV and POA that everyone wants to toss in the trash for cycling crap. Would be better to let the stock PCM handle compressor control. With the stock pressure sensor installed It'll handle the fans, under/over pressure, idle compensation, RPM cutout, etc. Facto...
by 71403
Mon Aug 13, 2018 4:01 pm
Forum: Automotive Air Conditioning Forum
Topic: strange cooling
Replies: 54
Views: 2308

Re: strange cooling

working right now on the 2nd injection system and can not get this thing above 13 mpg on 4 buck gas. I am vacillating between an LS and a Hemi. In either case if I use the compressor that comes with the engine it should solve the compressor at idle issue. Injection as in EFI? Fuel-wise the only thi...
by 71403
Fri Aug 10, 2018 8:18 pm
Forum: Automotive Air Conditioning Forum
Topic: AC Compressor Stopped Engaging
Replies: 16
Views: 508

Re: AC Compressor Stopped Engaging

The round pressure switch on the back of the compressor. Put a test light to that and battery positive compressor clutch engages Ah, ok, so exactly what a shop told you a few posts ago? Then you need a wiring diagram and figure out what's wrong, Can buy short term access from Mitchell or Alldata.
by 71403
Fri Aug 10, 2018 9:47 am
Forum: Automotive Air Conditioning Forum
Topic: AC Compressor Stopped Engaging
Replies: 16
Views: 508

Re: AC Compressor Stopped Engaging

When I hook up test light to battery positive and touch compressor wire harness from back of compressor - the AC clutch will engage and I get cold air. Need to specify which wire(s) you're talking about. Picture would help. Just not sure what the smartest approach would be money wise. Trip to a sho...
by 71403
Thu Aug 09, 2018 9:49 pm
Forum: Automotive Air Conditioning Forum
Topic: AC Compressor Stopped Engaging
Replies: 16
Views: 508

Re: AC Compressor Stopped Engaging

It's a switch, no polarity, so doesn't matter A vs B.
by 71403
Thu Aug 09, 2018 1:50 pm
Forum: Automotive Air Conditioning Forum
Topic: AC Compressor Stopped Engaging
Replies: 16
Views: 508

Re: AC Compressor Stopped Engaging

It's a lot harder without a real scan tool but here's a few basic steps 1. Verify the two 10A fuses in the underhood fuse panel for the compressor clutch and clutch relay supply are good. ("Ign E" and "A/C Comp") 2. With a/c requested from the HVAC control, verify +12 volts at hi...
by 71403
Thu Aug 09, 2018 11:38 am
Forum: Automotive Air Conditioning Forum
Topic: AC Compressor Stopped Engaging
Replies: 16
Views: 508

Re: AC Compressor Stopped Engaging

The engine computer controls the a/c clutch on that truck, there's many things non-a/c related that will cause it to not engage the compressor. Assuming gauge on death can is ballpark correct you have enough pressure to satisfy the cycling and low pressure switches - if it's not engaging it's an ele...
by 71403
Sat Aug 04, 2018 6:42 am
Forum: Automotive Air Conditioning Forum
Topic: Trinary Switch Selection
Replies: 1
Views: 144

Re: Trinary Switch Selection

Fan should come on with the a/c request not pressure alone. If using two speed fan(s) can use high pressure switch to activate the high speed. Ideally the fans should disable over ~30mph. The stock ECM doesn't control fans but if you're into tuning there are code patches and upgrades to allow for it.

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