1993 Jeep Cherokee A/C Performance Issues

[DetroitAC]

Evaps normally burst above 275 psig, I've seen some deform at pressures lower than that. It's normal duty for them to see maybe 170-180 psig in Arizona or gulf coast countries, that's 134a saturation pressure at 120F. R12 is going to be about 155 psig at that temperature. I leak check at 150 psig, never had a problem. A decent number of evaps dramatically burst in car paint booths

[bohica2xo]

The original condenser was a Serpentine design that worked well.

If it was replaced with an aftermarket part of a different type, it is hard to say if the condenser is up to the job.

Jeep went several years where they could not make up their mind on fans. I believe your 1993 should have an engine driven fan with a clutch, and an electric fan as part of the A/C system.

Some vehicles are listed with two electric fans. Does your vehicle have a mechanical fan?

[mtwask01]

The original condenser was a Serpentine design that worked well.

If it was replaced with an aftermarket part of a different type, it is hard to say if the condenser is up to the job.

Jeep went several years where they could not make up their mind on fans. I believe your 1993 should have an engine driven fan with a clutch, and an electric fan as part of the A/C system.

Some vehicles are listed with two electric fans. Does your vehicle have a mechanical fan?

Yes, this Jeep has a mechanical fan with a new OEM clutch. There is also an electric fan that comes on with the A/C. I'm not 100% sure the condenser is the issue given that the vent temps never really drop below 50-55 degrees no matter how long I've been driving unless it's cooler than say 80 degrees outside. I'm eventually planning on starting over with a new parallel flow condenser from a 97-01 Jeep, a plate fin evaporator, new expansion valve and drier. I can't find good information about how well these older system performed as most of these Jeeps on the road today don't have working A/C or have been converted to R-134a. I remember it working better with the original system but that was 2 years ago and I don't know how much I trust my memory at that point.

[DetroitAC]

I had an 88 Dakota with a 3.9L, AC worked very well, but was a standard cab, tiny interior. My evap was running below or close to freezing I think because i would get a faint mist coming out of the vents when conditions were just right. I think the airflow was pretty low compared to current trucks. I also think it was probably the same system as your Cherokee, so my feeling is you should be able to get nice cold air for the guy or gal that is paying the insurance/gas, but second row peeps not too happy.

[Cusser]

We had a 1984 small Jeep Cherokee in Arizona from 1988 through 1994 and it cooled well. We did have a couple of issues with the vacuum-operated vent "motors" but bought replacements at Jeep parts yard, taking my hand-held vacuum pump along to test before buying. And one day the AC compressor seized and new compressors were scarce and quite expensive, so bought a used compressor taken off a Cherokee as I waited for $75, same parts yard and that worked. This 1984 R-12 Jeep had manual service valves, so didn't even lose R-12 when I installed the used compressor, which did work.

Here in Arizona, the assumption is that 99% of the vehicles on the road have working AC or the drivers would wilt, so I had faith in that used compressor.

[Diametric]

Here is a list of reasons for a high side to be too high, from one of the masters (Ice-n-tropics):

Blocked circuit inside evaporator coil

I've never seen this? Is this a common occurrence?

Evaporator coil with internal by-pass due to faulty manufacture or over pressurization during service

Is this referring to something such as an internal seam separation? How would an evaporator core have an internal bypass other than a built in bypass such as found in industrial and high end (but not usually passenger car) evap cores?

[Cusser]

Your voltage observation is a good one. If you are only getting 12.5 volts at speed, then either you have a bad/corroded connector someplace or your alternator is shot. At speed, a modern alternator should put out a regulated 14.2 volts or thereabouts. Voltage lower than that will create a very high amp draw by the fans and the comp and put quite a drag on the motor.

If your voltage measured across the battery terminals with engine running at maybe 2000rpm is only like 12.5 volts, you may not be supplying enough voltage to keep the AC compressor clutch engaged.

3 decades ago, we had a 1984 Cherokee, and went to a work activity at a lake; halfway there, the AC cut out. When departing, I noticed the voltage meter on the dash was reading less than 12 (not sure if this model also had a charging warning light, I didn't see one), and we were able to make it home using lights but no AC. Turned out to be a faulty brush/broken spring in its alternator, which made easy fix as on top of its engine and $3 repair kit in stock at Autozone.

[JohnHere]

Note: This topic is four years old.

[Diametric]

Note: This topic is four years old.

All I saw was AUG 18...and thought it was yesterday. oops