Search found 198 matches

by GM Tech
Thu Oct 30, 2025 3:12 am
Forum: Automotive Air Conditioning Forum
Topic: Importance of "dust caps" for schrader valves
Replies: 2
Views: 20476

Re: Importance of "dust caps" for schrader valves

When I worked for Delphi Thermal, the refrigerant lines and hoses people informed me that the plastic caps are designed to be the primeary seals- thats why they have a rubber element or washer or seal in them. The shrader valves are there to hold in the refrigerant just long enough to get the caps ...
by GM Tech
Thu Aug 21, 2025 1:31 am
Forum: Automotive Air Conditioning Forum
Topic: I have questions about DIY charging
Replies: 4
Views: 39191

Re: I have questions about DIY charging

Sounds to me like the compressor is not running....
by GM Tech
Tue Jul 16, 2024 10:03 pm
Forum: Automotive Air Conditioning Forum
Topic: how much leakage from a Schrader valve is too much
Replies: 3
Views: 6344

Re: how much leakage from a Schrader valve is too much

That is how I test my leak detector- take off the caps and make sure it works...Then put caps back on.
by GM Tech
Mon Jul 01, 2024 8:14 pm
Forum: Automotive Air Conditioning Forum
Topic: Blend door theory/diags
Replies: 5
Views: 7170

Re: Blend door theory/diags

Typically all air flows through the Evaporator first, then gets directed through the heater core if warm/hot air is requested. It is diverted around the heater core if cool/cold air is requested. This is so while in defrost mode, dry air can be used on the windshield. So if you can't decide if it is ...
by GM Tech
Thu May 30, 2024 7:25 pm
Forum: Automotive Air Conditioning Forum
Topic: New Compressor and everything else - not cooling
Replies: 5
Views: 6720

Re: New Compressor and everything else - not cooling

A new condenser comes with a new OT in condenser outlet- make sure you don"t also have one in-line in front of Evap.
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: 7940

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 return ...
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: 15164

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 ...
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: 15164

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 ...
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: 6006

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: 16112

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.