Search found 193 matches

by GM Tech
Wed Aug 30, 2023 7:53 pm
Forum: Automotive Air Conditioning Forum
Topic: Trinary Switch without the high/low exist?
Replies: 6
Views: 1265

Re: Trinary Switch without the high/low exist?

Be careful-- lots of outlets call a 3-wire transducer a "trinary switch" Seen it many times. A transducer tells the ECM the exact pressure and the ECM decides when and how to control fan(s) etc. In a three-wire transducer, one wire is ground another is 5volt reference and the third is the ...
by GM Tech
Sat Aug 26, 2023 7:51 pm
Forum: Automotive Air Conditioning Forum
Topic: Adding high pressure switch to older unit help.
Replies: 13
Views: 2350

Re: Adding high pressure switch to older unit help.

I can remember on a 1991-94 GM Pick-up truck with the R-4 compressor a high-pressure switch mounted in the back of the old R-4 compressor that activated the recirc door automatically at about 250 psi pressure. Most all complaints were that the fan goes into a High-High speed on its own, and owners c...
by GM Tech
Sat Aug 26, 2023 12:21 am
Forum: Automotive Air Conditioning Forum
Topic: Adding high pressure switch to older unit help.
Replies: 13
Views: 2350

Re: Adding high pressure switch to older unit help.

Seems kind of silly to have pusher fans running when driving 60 mph down the road- Also if wiring into the compressor circuit, the spinning fan(s) will back feed the compressor clutch- providing current when the compressor is not running because they generate current by free-wheeling in the wind. Th...
by GM Tech
Wed Aug 02, 2023 9:19 pm
Forum: Automotive Air Conditioning Forum
Topic: All new A/C System Parts--> Big problem - Help??
Replies: 6
Views: 769

Re: All new A/C System Parts--> Big problem - Help??

Yes, that ERA of GM trucks had the same fitting on both the inlet and outlet of the condenser- easy to mix them up- seen it many times-- always remember that a condenser cools the hot gas in and it changes to a liquid as it flows downward to the outlet- where the OT usually is.
by GM Tech
Fri Jul 14, 2023 9:48 pm
Forum: Automotive Air Conditioning Forum
Topic: potential leak prior to evacuation/recharge - how to find
Replies: 14
Views: 2791

Re: potential leak prior to evacuation/recharge - how to find

I've seen equalized Low side/High side pressures of 275psi at Lake Havasu AZ at 120 degf ambient,sun-soaked hot engine shut down in Pontiac Formula doing hot soak testing- Black painted car- so yes the evaporator can take it.
by GM Tech
Sat Jul 08, 2023 8:32 pm
Forum: Automotive Air Conditioning Forum
Topic: New compressor, shuts off on high head pressure
Replies: 45
Views: 6059

Re: New compressor, shuts off on high head pressure

Yes, head pressure is high with two OTs in system-- go with factory method of using the OT in the condenser outlet only if it is a front only system! Aftermarket only wants to build one condenser for all Utility vehicles and let the mechanic figure out if it needs an OT or not. I've seen new condens...
by GM Tech
Fri Jul 07, 2023 9:37 pm
Forum: Automotive Air Conditioning Forum
Topic: New compressor, shuts off on high head pressure
Replies: 45
Views: 6059

Re: New compressor, shuts off on high head pressure

Biggest problem I've seen with dual systems is having two orifice tubes installed-- Those condensers all come with an OT in the outlet- yet a dual system has it's OT just beyond the split in the liquid line to the rear. So make sure you don't have an OT in the condenser outlet- and you do have one i...
by GM Tech
Tue Aug 16, 2022 11:42 pm
Forum: Automotive Air Conditioning Forum
Topic: First AC Job
Replies: 9
Views: 2204

Re: First AC Job

May have an a/c code set---unhook battery for 10 sec and see what happens
by GM Tech
Mon Aug 15, 2022 8:31 pm
Forum: Automotive Air Conditioning Forum
Topic: My R4 compressor never cycles, either
Replies: 4
Views: 1453

Re: My R4 compressor never cycles, either

Adjustable cycling switches haven't been used for over 30 years---Everything used on GM vehicles are non-adjustable--(no screw between terminals). Cycling switches are there to avert freeze-up and low refrigerant charge (pressure) ruining your compressor. If it is not cycling- it's most likely the s...
by GM Tech
Sun Aug 07, 2022 12:36 am
Forum: Automotive Air Conditioning Forum
Topic: 2000 Silverado Hi side port leaking
Replies: 18
Views: 4506

Re: Seized Hi pressure Port

I use vice grips to grip up high- who cares if the sealing area gets marred- I'm replacing that part....