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AC cycling on and off but no cooling

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New User

Jul 18, 2016, 8:42 AM

Post #1 of 4 (988 views)
  post locked   AC cycling on and off but no cooling  

2004 Ford Ranger, 6 cylinder 4.0, 170K miles

Bought this truck used about a month ago. Had good AC when I took delivery then after three weeks nothing but warm air. The compressor cycles on and off. Mostly off. You can here the low side relay clink in and out. Pressure on the low side, measured using one of these $20 filler hoses with attached gauge, is around 20 when compressor cycles on then goes up to around 40+ when compressor goes off.

Thought maybe there was a leak. Did not see any obvious oil around compressor shaft so I bought a can of this $40 Red Angel Stop Leak and added it to the low side. Still cycles but now pressure is around 40 when compressor spinning and up to 70 when off.

So here I sit. Not going any further until I get some guidance. Do I have a restriction somewhere?

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 18, 2016, 9:07 AM

Post #2 of 4 (981 views)
  post locked   Re: AC cycling on and off but no cooling  

Those are aptly named "DEATH KITS"
Now any chance to fix the so common leaks that are the cause of most lack of cooling is contaminated with the junk you put in it.

I can't keep writing a whole book on this but A/C isn't DIYable for most anything to do with refrigerant which may not have even been the problem and now is.

Do yourself a huge favor and send it out and please tell the pro A/C shop it has sealer in it so they don't wreck up to $10,000 bucks worth of equipment fixing yours.

Not trying to blame you as the advertising that it's so easy and simple with those dang kits is plain wrong, harmful and destroys chances of a reasonable cost to fix what was really wrong in the first place. Sorry you believed that lie,


New User

Jul 18, 2016, 9:23 AM

Post #3 of 4 (976 views)
  post locked   Re: AC cycling on and off but no cooling  

Actually, this specific product has a good reputation and if there is/was a leak should have fixed it as long as it is not in the compressor. If no leak was there then it will mix in with the coolant and no harm done. Again, this specific product not the cheaper ones.

That said, if there is a restriction then I am back to square one.

How about giving me some suggestions as to what to look for?

What does it mean when the compressor cycles on and off from 20 PSI when running to 40PSI when stopped?

(This post was edited by rangerandy on Jul 18, 2016, 10:04 AM)

New User

Jul 18, 2016, 10:53 AM

Post #4 of 4 (958 views)
  post locked   Re: AC cycling on and off but no cooling  

Never mind. I have my answer. Working great!

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