Can rear A/C simply be bypassed?

[beachsuburban]

Would it be this easy? I'm at the beginning here but the plan is to get some ac up front while eliminating the rear. The system has not been operational in years. I rented the A/C gauges and vacuum pump from parts store. I already picked up the Four Seasons 56373 Discharge and Suction Line that is for front A/C only and a new O-ring kit. Currently have the Genuine Parts 15-1681 Accumulator and the ACDelco Professional 15-5754 Orifice Tube in the cart ready for checkout am I missing anything??

- Now on the condenser line that goes to the evaporator, I need a way to close off the rear line connection. Any suggestions on that?? Thinking of welding the tube that I cut off where it was crimped to the rubber hose, new O-ring and put it back in.
I was going to do the "weld" on the condenser to evap line, hook everything up and run a pressure test, when I get the system to hold pressure then change out the old accumulator and orifice tube and re do the pressure test. If successful then.. .

- It has the 57237 compressor and also has the 134a Schrader valve. Plan there is to use around 30 oz. of 134a and 8 oz. of Pag or ester oil. Thoughts on this?

Is there anything I'm missing here?
Thank You!!

 

[gmbellew]

Guess my question is - why don't you want the rear AC operational if you habe all the components?

 

[beachsuburban]

All the rear components on the roof have been removed.

 

[gmbellew]

All the rear components on the roof have been removed.

Gotcha. Not using the rear and a lesser charge will work. If you have a front only hose set, wont the rear lines be fine as is? What do you need to block off?

 

[beachsuburban]

The original Discharge and Suction Line had a "Y" in the pipe to go to the rear, I just got the new one for front only A/C models only so that is solved . As for the other line that goes from the condenser to the front and rear evaporators, that is also split but via threaded connectors. This part is a little harder to find and it seems easy enough to close it off.

 

[gmbellew]

The original Discharge and Suction Line had a "Y" in the pipe to go to the rear, I just got the new one for front only A/C models only so that is solved . As for the other line that goes from the condenser to the front and rear evaporators, that is also split but via threaded connectors. This part is a little harder to find and it seems easy enough to close it off.

I'd close it off in a way that it could be restored in the future if possible. It will still work fine in the front. I had my rear TXV clogged up once. The front AC was still cold....just no circulation through the rear lines.

 

[YakkoWarner]

A threaded cap may be all you need, with appropriate o-ring or gasket to hold the prerssure. I have the opposite problem - my rear AC gets cold but the front is barely below ambient air temp. Unfortunately all the plastic baffles inside the rear unit had cracked and broken away so although the evap gets really cold and the fans spin freely very little air actually comes out.

 

[beachsuburban]

I thought about the treaded cap and wasn't sure about the way the oring would seat, what "plug" i did see online looks around $30 and im not even sure if it's the correct part

 

[82SquareBurb]

FWIW If you just need to plug the threaded -6 female in the liquid line, you can use one of these: https://www.amazon.com/dp/B07VCB7SMG/

Then just use a -6 cap to block that off. I never found an actual plug that would work. Brazing the old fitting shut should work as well in a pinch.

 

[iiixtremeiii]

Would this work?

Rear AC block kit Old Body Style Suburban 1985-1990

Rear AC block kit Old Body Style Suburban 1985-1990, 1985 | 1986 | 1987 | 1988 | 1989 | 1990, 1985, 1986, 1987, 1988, 1989, 1990

www.streetrodguys.com

 

[Hunter79764]

On the charge and oil, yes, just treat it like a similar year truck without rear AC. I believe those are good starting points, but charge to the correct pressure and temperature for the outdoor conditions you have. Engine at high idle, windows down, passenger door open and AC on max is how I like to have it. Charge to the right pressure, then adjust your low pressure switch to around 25 psi as a starting point. That controls where the compressor kicks out, and the goal is to get the evaporator as cold as possible without making an ice block out of it be getting below freezing too far. On a suburban without rear air, you probably want as much capacity as you can get...

Speaking of nice-to-have/extra capacity, if you don't have a parallel flow condenser (the ones with flat plates and little zig-zag fins), that will help get more capacity out of the system vs the older round tubes stabbed through stacks of plate fins. A Single cab truck doesn't really matter that much, but in a giant greenhouse of a suburban, the extra capacity is nice.
Your compressor is "fine" with r134a, but I haven't had the best luck with R4's (even/especially reman units) and the extra pressure of 134a will work it a little harder. i.e. don't be surprised if the next component is a compressor in a few years. A modern condenser coil will help it live the longest by keeping head pressures low, as will electric fans/booster fan if possible.

For information on some of the other situations, if the rear AC is in place but non operational (as mentioned with the clogged TXV) the additional refrigerant is "stored" as liquid in the high pressure line going back to the rear unit, which is why it doesn't have problems with the "extra" refrigerant. And when a parallel system is low on charge, the TXV will adjust and the orifice will not, meaning the rear AC gets cold and the front suffers. That could also be impurities in the refrigerant, doing the same thing. The TXV will make the rear cold at the expense of the orifice, but you can't have two orifice systems or two TXV systems parallel without endless fighting each other.