AC issue, odd pressures from compressor (1 Viewer)

[racingjason]

Hello all,

The AC on my 1989 HJ61 suddenly stopped working after sitting for about 3 or so weeks. It has always worked well and fires right up in the spring. We added some R12 to it about 5 years ago and it has been great ever since...until today. Luckily my Dad has the necessary gear so after some fiddling around we extracted all the R12, vacuumed the system and recharged. We could find no evidence of leaks with the UV light (there was dye inside) and the vacuum held for 3 or so hours at 25(ish) in-hg so we thought it would be fine. Turns out it just does not work. Clutch kicks in from the dash switch but it does not seem to build enough pressure on the high side and the low side is too high (really almost equal during some checks. None of the lines or fittings really get cold. I read in another thread that there could be an internal leak causing things to bypass so I was just wondering if anyone had encountered this before I stepped up for a new compressor. The odd thing is that the compressor is quiet and gives no indications of failure.

 

[ceylonfj40nut]

Check your expansion valve. It would be good to share the pressure readings for better advice.

 

[Michael Hanson]

HI, Without knowing the nos. it sounds like your receiver- dryer needs replacing. Mike

 

[racingjason]

I believe it was 100 psi on the high side and 80 psi on the low.

 

[Michael Hanson]

Try receiver -dryer replacement first. Mike

 

[racingjason]

Thanks Mike, that is an easy and relatively cheap fix to try. For my understanding, how can the dryer create this problem? Is it a restriction issue?

 

[SteveH]

I had this problem on my '98 4Runner, replaced the receiver dryer to no avail, and ended up replacing the expansion valve (a lot more work). A/C now works fine. Don't condemn your compressor just yet. Like many, I replaced the receiver/dryer first, because it was 'easy', which is a lot like looking for the lost wedding ring at night under the streetlight (because that's where the light is).

 

[racingjason]

Thanks SteveH, good to know! I was thinking of changing them both despite the difficulty. I was having a hard time believing it was the compressor as it failed while sitting for a few weeks and it makes no more noise than it should. I could the valve getting 'sticky' however.

 

[Michael Hanson]

Hi, Yes would be a restriction. Also why your readings would be similar. Mike

 

[vipergrhd]

If expansion valve don't fix this issue it's your compressor.

 

[86aggie]

i reread your original post to be sure that you had vacuumed the system. No one has mentioned this, so I want to be sure it is out there. When we see fluctuating pressure, it is usually due to a inappropriate mix of coolants that are not compatible, and as they cycle thru, they change the pressure. Doesn't sound like that is the issue, given the vacuuming....