AC Replacement Parts?

[robfg67]

I have a '90 MJ with the 4.0 engine and factory ac. There is no charge left inside the system and I want to convert to R134a.

 

The website JeepAir.com has all the parts that I need:

 

Compressor Kit $279

Condenser $120

Evaporator $140

Liquid Line Drier to Condenser $52

Discharge Hose $35

Suction Hose $87

Quick Disconnect Eliminator Kit (needed because they don't have the other liquid line) $100

 

I'm sure that their parts are high quality, but wow is this expensive.

 

Is there a better/cheaper way to go to get my ac back in order?

 

 

 

 

[cruiser54]

Yes. 

 

Find and fix the leak. Then do a simple 134a conversion. 

[JefCooks]

^ this. Get some uv dye in the system and find the leak. Probably just an o ring which you should replace all of anyways, clean system well, add oil and reload. It’s shockingly easy to convert to r-134

[cruiser54]

THIS^^^

Don't drink the AC and Parts guys kool-aid. 

[eaglescout526]

Caution with jeep air. If you buy their R134a fittings, they might come ovaled and prevent proper tightening. 

[AZJeff]

Unless parts of your existing system are damaged, worn,  or missing, there is no reason you have to replace all of the pieces when converting to R134a.

 

The heat exchangers in the system (evaporator and condenser) would probably benefit from a flush.   The existing lines will probably be oil soaked with R12 oil, so they will provide enough of a barrier to prevent R134a molecules from leaking through the old "non-barrier" style hoses.

 

Changing the accumulator (receiver/drier) is HIGHLY recommended, of course.  You will also need new R134a compatible oil for the system.

[robfg67]

All great points.

 

Just a couple more questions...

 

1. What is the pressure that the system should be tested at. Residential central systems are pressure tested at 150 psi and mini splits at about 500 psi with dry nitrogen gas. I can test the system without any additional help.

 

2. I thought that a R134a conversion required that all those parts be replaced. What is involved/required to do the R134a conversion you recommend? 

Is there a DIY write up that I can follow or a kit that you recommend?

 

Thanks again.

[cruiser54]

Nope. Not necessary to replace all that stuff. 

 

 

[robfg67]

So I was able to pick up a 1/4" male to 3/16 female adapter and did a pressure test at 100 psi for 30 minutes and no pressure drop...yes, the king valves were open.

 

I then removed all the nitrogen gas, got the gauges out of the way, started up the engine, turned ac on and jumped out the low pressure switch, and the compressor clutch engaged. I only ran it for 2 seconds as there is no charge in the system.

 

So not sure where the R12 charge went, but there are no leaks and the clutch engaged.

 

What should be my next step?

[cruiser54]

Get 134a fittings, some 134a with dye in it and the correct PAG oil for the conversion. 

 

The system will need to be evacuated. 

[robfg67]

Cruiser, what are your thoughts on vacuuming it down and adding R12 back in? Yes, I know it's expensive.

[cruiser54]

I've always converted to 134a. 

[robfg67]

Hey Cruiser54,

 

Just looking through your Renix website-good stuff!

 

In the bypassing the comfort switch tip, does the black wire to the switch just stay in that position?

 

 

[cruiser54]

I don't understand the question. 

[AZJeff]

11 hours ago, robfg67 said:

Cruiser, what are your thoughts on vacuuming it down and adding R12 back in? Yes, I know it's expensive.

The conversion to R134a should not be very expensive, especially if all the existing system parts are in good working order.  In fact, I would say it would CHEAPER to convert than to stay with R12.   Having done several conversions, here is my advice:

 

If your existing hoses are all in good condition, with no cracks or dry rot, they can be used as is.  However, ALL of the o-rings that join those hoses to the various parts of the system will need to be replaced.  The old o-rings will be dried out and are likely to leak with the smaller molecules that are present in R134a.

 

The condenser and evaporator can be reused.  If you want optimum performance, it would be beneficial to flush those two items with a refrigerant flushing agent, and blow them out with compressed air while they are disconnected getting new o-rings installed.  The idea behind flushing them is to try to drive out as much of the old R12 compatible refrigerant oil as possible.  It's not harmful to leave it in the system, but the old oil will reduce system capacity and function to some degree.

 

I would recommend taking the compressor off and draining as much of the old oil out of it as possible for the same reasons you want to flush the condenser and evaporator.

 

Installing a new receiver/drier (accumulator) is a must.  This item has a dessicant in it that is probably long since used up, and since you have the system apart, it has probably sucked up some more moisture during that process.

 

When you fill the system with new R134a compatible oil, you should fill various parts of the system based on this ratio:

1.  the accumulator gets 50% of the total oil for the system

2. the condenser gets 12% of the total oil for the system

3. the evaporator gets 25% of the total oil for the system

4.  the compressor gets the remaining oil 

 

I don't have the numbers for how much oil your model year takes, unfortunately.

 

As far as how much R134a refrigerant to use, the rule of thumb is to fill the system with 80% of whatever amount was supposed to be used when the system was charged with R12.

[robfg67]

Cruiser,

 

You wrote:

 

"Plug one end of the jumper wire in the cavity for the tan wire and the other in the cavity for the striped wire of the harness and you’ll be in permanent Power mode."

I'm assuming that the black wire cavity stays empty. I worded my question incorrectly.

[robfg67]

Jeff,

 

Thanks for this info. Exactly what I'm looking for.

 

Do you have a recommendation as to where to purchase the drier, new 0-rings, and the proper oil?

[cruiser54]

4 hours ago, robfg67 said:

Cruiser,

 

You wrote:

 

"Plug one end of the jumper wire in the cavity for the tan wire and the other in the cavity for the striped wire of the harness and you’ll be in permanent Power mode."

I'm assuming that the black wire cavity stays empty. I worded my question incorrectly.

You are correct. 

[AZJeff]

7 hours ago, robfg67 said:

Jeff,

 

Thanks for this info. Exactly what I'm looking for.

 

Do you have a recommendation as to where to purchase the drier, new 0-rings, and the proper oil?

I normally buy stuff like the receiver/drier from a reputable place like Rock Auto.  At least that way, you get some decent brand name stuff.

 

The O-rings can be had at virtually any auto parts store, as can the oil.   The later Sanden compressors use PA100 oil.   I don't know what the older ones use, but lacking any other suggestions from the forum, I would assume the PAG100 would be acceptable.