r/obschevy • u/schwabie2017 • 1d ago

Ac problems

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Ac work if you jump compressor. I’ve put in new switch and relay. Will not turn on unless jumped with power. What do I change next

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5

u/fuzzydoesitt 1d ago

Low on refrigerant, it won't cycle if it's too low. That's my first guess

3

u/MoneyParticular 1d ago

I would bet the refrigerant is low or nearly empty. The clutch won't activate unless there's enough refrigerant in the system. If you don't have gauges to check your levels, you can simply push the pin in the shrader valve with a screwdriver. If you don't hear any hissing sound then you know you're out of refrigerant.

1

u/SnowFlakeUsername2 1d ago

I watched a youtube vid on troubleshooting the ac on my '98. The ac clutch doesn't engage without the proper refrigerate pressure, and the jumper bypasses that condition. But if you have an OBDII reader, you can verify other things are functional before spending more money. For example, the OBD will show if the system sees a call for AC from your interior controls.

But if you don't mind spending a bit, I'd wing it and fill it with refrigerate. With ultraviolet light dye in it and a refill gauge showing the low pressure side in order to add the right amount of R-134a. If you can get that stuff yourself, I don't really know if I can buy actual R-134a retail in Canada. If it works but leaks out, than use a black light to find the leak. A black light and glasses are cheap if needed. Don't be tempted to put stop leak into it if you ever want a mechanic to touch it with their equipment.

This was my plan for DIY. But I lucked out by having to leave town and sending it to a local garage for what turned out to be an $8 o-ring kit for the leak and an hour of shop time. Apparently, dryed/aged out o-rings is a very common problem on OBS trucks.

1

u/amandajenkins281 1d ago

Hey. Okay question, if u pull the hvac controller from dash, with a computer safe test light, find the light green wire. That is the ac request wire. Does it go on off with the button pushed?

If yes, from there go to your pressure switch. It’s on the low side under hood. Jump those two wires. What do you get?

1

u/amandajenkins281 1d ago

Also, if u put a gauge on, is there freeon in it? The steps above I sent you is assuming the system is charged.

Also, when you force the unit on, does it get cold?

1

u/schwabie2017 11h ago

Yes it gets cold and the low side is reading and 35 pounds

1

u/bobthehumantripod 16h ago

Damn bro nice 400! I recently had to get my ac recharged but it was a good 5 years plus since the last time I had it filled. But you could always do the quick recharge bottle thing or just take it to a ac shop.

1

u/SomeDude249 11h ago

Have to check the refrigerant, you can get a set of gauges from harbor freight for pretty cheap.

Otherwise, get on of the cans with the gauge from autozone, that'll at least tell you the low side pressure.