AC problems, it has refrigerant and compressor works

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NTX JK
Posts: 1
Joined: Fri Jun 01, 2018 6:44 am

AC problems, it has refrigerant and compressor works

Postby NTX JK » Fri Jun 01, 2018 6:57 am

I have an '07 Jeep Wrangler JK and this past August, the AC compressor would cycle on and off. I didn't mess with it too much at the time. Now that the temps are getting up to 100 this week, I have been trying to diagnose it. It has enough freon (48psi/220psi), the compressor works when I connect it straight to the battery. I have already replaced the pressure switch and that did not solve the problem. The pressure switch has 3 wires, and I know when I check the voltage, it has 5v going to the sensor, but only around 2.2 with the new sensor. I jumped the 5v power supply to the power signal, and that did not turn the compressor on. The pressures seem normal when I jump the compressor to the battery, but when I disconnect it from the battery, the pressures even out between the low/high side. Is that normal when the compressor is off? Any ideas what else I should check?
JK AC Wiring Diagram.jpg
JK AC Wiring Diagram.jpg (246.53 KiB) Viewed 419 times
71403
Posts: 39
Joined: Fri May 27, 2016 12:46 pm

Re: AC problems, it has refrigerant and compressor works

Postby 71403 » Fri Jun 01, 2018 2:18 pm

Start with seeing if the ECM is commanding a/c clutch engagement to the TIPM. Unfortunately this is one of the ones where a real scan tool is almost mandatory because there's so many things that can inhibit operation.

> the pressures even out between the low/high side. Is that normal when the compressor is off?

:roll:
JohnHere
Posts: 105
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate

Re: AC problems, it has refrigerant and compressor works

Postby JohnHere » Mon Jun 04, 2018 8:16 am

I don't think you mentioned whether it's cooling. But based on your higher than expected LP reading (at an unknown engine RPM and ambient temperature), I'd bet vent temps are rather warm.
Since it's impossible to tell from pressures alone whether a system is properly charged, I think I'd start be recovering and weighing the charge, then evacuate and recharge by weight. At the same time, I'd add a little UV dye and check for leaks. It's certainly possible that an 11-year-old vehicle has leaked-out enough refrigerant to begin giving cooling problems.
I think your vehicle has a CCOT system. If so, compressor cycling is normal.
JohnHere
Posts: 105
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate

Re: AC problems, it has refrigerant and compressor works

Postby JohnHere » Mon Jun 04, 2018 12:25 pm

Oh, and I forgot to mention that it is normal for both the LP and HP to be close to the same when the system is off and that they'll roughly equal the ambient temperature.

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