A/C compressor not cycling on

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K-Man

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I just noticed today that my A/C ‘94 350 is blowing hot and compressor is not cycling on. It seemed to just stop blowing cold. After a little research I tried bypassing the cycling switch with a jumper and compressor kicked in. Thought it was the cycling switch so bought a new one and same problem. Is there anything else that controls the compressor engage? Can low Freon cause it not to cycle? Should it cycle no matter what? Is there a chance the new one is bad too? Replaced with GM part The A/C was rebuilt about 4 years ago.

Thanks for your time!!
Kevin
 

Schurkey

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Low refrigerant is THE most-common cause, if it's warm enough for A/C.

If the refrigerant charge is low, you have a leak or it's too cold out.

If you have a leak, you might as well replace EVERY O-ring seal in the system, after verifying that the evap, condenser, compressor are not leaking. While you're in there, probably a new orifice tube, too.
 

1998_K1500_Sub

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I guess it’s time to buy a uv light and take a look.

Yup.

For the benefit of those with a similar problem, don't try to jerry-rig the AC to run by shorting the low-pressure cycling switch. Oh yeah, the compressor will run... but due to the low (or no) refrigerant charge the PAG oil, which normally gets carried-along by the flow of refrigerant, won't circulate in the system and the compressor will get very unhappy.

(forgive me for stating what's obvious to some)
 
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Schurkey

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Frank Enstein

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Yup.

For the benefit of those with a similar problem, don't try to jerry-rig the AC to run by shorting the low-pressure cycling switch. Oh yeah, the compressor will run... but due to the low (or no) refrigerant charge the PAG oil, which normally gets carried-along by the flow of refrigerant, won't circulate in the system and the compressor will get very unhappy.

(forgive me for stating what's obvious to some)
I would much rather be told something I already know than not be told something that will help!
 

Dariusz Salomon

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Dariusz Salomon

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Some parts stores have a UV light in their "loaner-tool" assortment.

I've got this one on my Amazon wish-list; but I don't know that I'll ever actually buy it.
www.amazon.com/dp/B000IHJXHG/?coliid=I2XYC1KIP6ORVH&colid=31ORN63IXRW6M&psc=1&ref_=lv_ov_lig_dp_it

xc_hide_links_from_guests_guests_error_hide_media
Just have someone to put pag with uv next time you recharge-or discharge and recharge with pag with uv-or top up-and get the torch I mentioned earlier-it's the same.
 

K-Man

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Well, UV light tells the story. Compressor failed and blew Freon all over everything. Now it’s time to decide if I wanna put more $$$ into it. Summers here in Northern California can get up to 110*. I dunno at this point. Thanks everyone!
 
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