Ac compressor, is this nornal?

[thegipper]

First off, my ac is blowing cold. Infrared temp gun says it's 40 degrees or lower when I aim it down a vent.

Like an idiot, I thought my freon might be a little low (before I checked the air temp) so I hooked up my basic ac gauge (low side gauge only that has the standard freon can hookup) and starting putting more freon in. I only did this for maybe 20 seconds before the ac compressor turned off, 10 seconds later back on, 10 seconds later off again and so on so I unhooked it.

Low side pressure was measuring about 36psi when the compressor was on at idle. If I reved it up to 2k rpm, the low side will drop to about 27psi.

This "compressor on off thing" only happens when it's idling after a few minutes. If I shut it off for a little while and start it back up again, the compressor is on the entire time until it does the on off thing.

AC on full blast while messing with it.

Here is a video of it cycling on and off after idling for a few minutes. It's about 88 here today. Oh, and it's dripping water like crazy like normal.

https://youtu.be/nY9DtwUKBQ8

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[thegipper]

I forgot to mention, it seems like the low side psi slowly raises before the on/off compressor thing starts happening.

I don't want to screw up a otherwise working ac system (shouldn't have touched it the first place but like I said, I'm an idiot)

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[azrex]

I'm guessing that it's overcharged and the high pressure switch is shutting the compressor off, then the pressure drops and it cycles back on and repeats. This will overheat the clutch coil and cause it to fail. Without gages to know the high-side pressure I can't be sure, but I'd try letting out some refrigerant and see if it stops the rapid cycling.

 

[thegipper]

I think you may be right. When I got this truck from my bro, the ac did not work. He said it works fine but has a slow leak so I recharged it using the same setup. I put in to much and if my memory serves me right, I had to let some out for it to stop cycling on and off.

I'll go give that a try

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[thegipper]

Yup, it was over charged. It used to leak because my brother said he had to put a can in it every spring. For whatever reason it must not be leaking anymore.

Lesson here: if it ain't broke....

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[JRZEE2000TR4LTD]

I think you may be right. When I got this truck from my bro, the ac did not work. He said it works fine but has a slow leak so I recharged it using the same setup. I put in to much and if my memory serves me right, I had to let some out for it to stop cycling on and off.

I'll go give that a try

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There seems to be an ongoing theme of people trying to diagnose an AC system without gauges. It just not possible in most situations. Get some gauges and do it right. That being said there is no separate pressure switch. Only one in the system which is dual acting. It opens at 28psi and 455psi. Since it's on the low side, 455 psi on the low side is bad, but less than 28 is also bad because the refrigerant will liquefy and slug the compressor. I suggest emptying the system, vacuuming it down for a while (the longer the better) and put in the correct amount of refrigerant (about 23oz) You can then use the sight glass on the drier to see if your charge is good (which it should be).

EDIT: Glad you fixed it. You're lucky. You could have really messed up the system

 

[thegipper]

I'll have my mechanic buddy hook it up to their AC machine and properly vacuum/fill it. He's done it for free for me, why I didn't just have him do it, is why I'm an idiot...lol

Thanks!

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[flipty]

I'll have my mechanic buddy hook it up to their AC machine and properly vacuum/fill it. He's done it for free for me, why I didn't just have him do it, is why I'm an idiot...lol

Thanks!

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I just had this with a Honda Fit that I just bought. I don't have the equipment to properly evacuate extra refrigerant so I was happy to pay them $75 for an evac and recharge. Now it's like being in a freezer inside the car.

SAME problem. AC on, car is not happy. The AC turns on and off over and over. I googled it (as I do with most things) and found that to be the obvious answer.

 

[LittleCaesar]

Forgo using the temp gun, they aren't accurate and often read lower than the actual reading. I don't know why though.

Buy yourself one of these. I have two or three. Usually within two degrees of the actual temperature:
https://www.amazon.com/Taylor-Preci...500427184&sr=8-7&keywords=digital+thermometer

An owner of automotive repair shops once told me that refrigerant in a can allowed him to buy a 36ft fishing boat and keep it docked at a slip the entire year.

 

[thegipper]

I have a calibrated digital thermometer at work I could use to know for sure what the temps are but the infrared gun I got is relatively accurate for what I use it for.

Yeah I'm not even sure why I bought one of those stupid cheap AC gauge kits, total waste of money.

Oh well...

 

[Majindan]

I have a calibrated digital thermometer at work I could use to know for sure what the temps are but the infrared gun I got is relatively accurate for what I use it for.

Yeah I'm not even sure why I bought one of those stupid cheap AC gauge kits, total waste of money.

Oh well...

Just a quick reminder to clean your condensor coils as well, really helps when the A/C is under heavy load/heat.

 

[thegipper]

Just a quick reminder to clean your condensor coils as well, really helps when the A/C is under heavy load/heat.

I actually just did this a couple weeks ago. I bought a couple cans of that AC cleaner at Home Depot, it worked pretty well.