QuestionQUESTION: Hi David--
I am replacing the A/C compressor on a 1996 GMC Suburban K1500TD (diesel) with rear air. I have the technology (though past success doesn't necessarily predict future results. :-)), but have a question or 3...
1) The original (assumed--bought vehicle used) compressor has an electrical connector at its rear; the new one (Global--new) does not. Apparently the original one is a redundant high-pressure switch, as shown in the AlldataDIY pages, though location is a bit vague--wire colors match. It is in series with the other switch. It seems to be in addition to, and set nearly the same as, the one on the connector block high-side line. With no further info, my tendency is to short the connections, tape it up, and let the other high-side switch do the protecting. Do you think this is a reasonable choice?
2) I'm also replacing the condenser and all the pieces parts inside from the compressor, along with replacing the orifice tube with a GM "filter" with tube inside. The new condenser (Modine, from the Thai condenser experts) is just over 1" thick versus original dimension of 1.5". I rechecked the spec with NAPA and they verified that it is the proper callout, and that the spec is the same with no distinction between rear air vs. no rear air. Do you feel this will give me the same results?
3) (Last one) I mentioned as an addition to one of your answers about trying to loosen the high-side line into the rear evaporator and the problems involved due to steel nut on aluminum male fitting. I don't predict success here. I have not used the rear air in months--since long before the compressor had its fit. Do you feel like I HAVE to clear this line? If the unit has not been called upon, would the expansion valve still have allowed refrigerant circulation through it, thus admitting the compressor pieces parts? Is there a strainer before the expansion valve?
I really appreciate your conducting this forum; how do we users properly show our support???
Thanks!
CapnAmerica in TN
ANSWER: Charlie,
"Though past success doesn't necessarily predict future results." I like that... going to have to use it in the future.
OK, asnwer 1. As long as you retain one of the high pressure switches in operation you will be fine. And I agree it would be much easier to leave the existing one in operation rather than re-wire the new. Just make certain that one of them is being utilized, you sound as if you know what you are doing, so I won't go into everything that can happen should you bypass them both.
Answer 2. The condensor depth is not so important as the width. What is important is the area that you will have airflow across. The shallower depth may come into play when you recharge the system however. Make certain you do not put the full amount of refrigerant back into the system. Stop a little short while charging it by weight, and finish it off by pressures.
Answer 3. The rear expansion valve would have allowed refrigerant to flow through, it never completely closes, however, prior to the line going back to your rear air, you should have a solenoid valve somewhere in the system, that would not allow refrigerant to flow through this line without you using the rear air. But on the outlet of the rear evap, there is no such valve, so the refrigerant may have been able to "backflow" into the line. Not likely though. Of course I would recommend that you flush this line also, but if you do not, the results will still, more than likely, be just fine. And no, in most cases there is not a strainer before an expansion valve.
As for showing support, all we ask is that you rate our answers. Someone on here helped me out when my riding mower crapped out on me, and in the end he saved me close to 700 bucks, that's why I started. Since then it's been just something to do to wind down after work.
But thanks for your question, if I was of any help, please remember to rate this answer. If I can do anything more to assist either now or in the future, do not hesitate to ask. Good luck in everything.
---------- FOLLOW-UP ----------
QUESTION: Q1 & Q2, about what I thought and planned without your confirmation of my thinking process. On Q3, if there's a solenoid, it is well hidden. WhenI could not loosen the fitting, I cut the line over the rear wheelhouse; it was FULL of crud and compressor shavings. I squirted it out with brake cleaner (non-chlorinated-tip from a local mech) and blew it out with air, then installed in the cut line the filter I had bought to use with the front evaporator...have to wait till Monday to buy another. NOW there's a strainer in front of the exp valve!
I picked up the "...past success..." remark from a stock prospectus; the govt lawyers make the shysters say that even while they are lying through their teeth trying to get you to buy their financial gizmoes.
I do what you're doing with the local folks in the computer realm, keeping them from buying the latest model computer to play solitaire and do email, just because Bill Gates timebombs all his operating systems!
And thanks a million for your prompt response!
Charlie Jones, aka CapnAmerica in TN
AnswerCharlie,
You had gotten me curious, so I thought I would look it up on my online service (Mitchell1-ondemand5) (I tried alldatadiy and wasn't terribly impressed, it was good but not what I needed) and as it turns out, you don't have a valve shutting off the rear. So that was bad info on my part, and I apologize. So now I am not surprised when you said you found a bunch of crud in that line. I am not certain as to whether or not you have, but with that information, I would highly recommend you flush your rear evap with a flushing agent also.
As for that tip from the mechanic, I don't recommend brake cleaner to clean out the refrigerant lines... for the simple fact that it is primarily for oil and grease type contaminants. The issue with having a compressor burnout is more metal shavings. these need to get carried out of the line by some sort of liquid flowing through it. You can buy the flushing kit from autozone-type shops for about 20 bucks and it works much better.
And finally, I responded to your follow-up because the allexperts.com powers that be count it against us if we let a question sit in our cue for a period of time.
So, once again, thank you for your question, and please remember to rate this answer. And expect a response from me in the future, if you don't mind, regarding this laptop I am using. It's 4 years old, and me being the cheapskate I am, want to upgrade, but not pay the new computer price.
Alright now, take care and good luck in everything.
