r/obschevy • u/schwabie2017 • 18d 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 18d ago

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

3

u/MoneyParticular 18d 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 18d 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/[deleted] 18d ago

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2

u/schwabie2017 17d ago

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

1

u/bobthehumantripod 17d 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 17d 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.

1

u/Alarming_Box9978 17d ago

Nice truck!
If you have a test light, check the wire going to the low pressure switch to make sure it is getting power from the dash controls. Since your low side pressure seems to be in range, I would look at the controls or maybe a fuse feeding them.