Grand Wagoneer Air Conditioning

In continuing to troubleshoot my way through my Grand Wagoneer's mechanical problems, I turn my attention now to the Air Conditioning System. My 1987 GW has Factory Air Conditioning.

When selecting "AC" on the Air Conditioning control panel, nothing happens, i.e., no fan, no air, etc. Unlike selecting any "heat" or "defrost" selection.

What does this mean, in terms of what I need to do to restore the functionality of the A/C System. It seems to be a given that I would need to have the A/C compressor charged, but any suggestions beyond that?

Thanks!

Reply to
randallbrink
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Well, the compresor will not run if either of the two pressure sensors have failed. The one on the accumulator is the low side, the one on the compressor is high side. Problem is your system is R-12 and they don't sell it to the public anymore. A good AC repair place should have it. Both sensors should ohm out at near zero if the system is properly charged. The high side opens if pressure gets too high and the low side opens if pressure is too low. A quick check to see if the problem is low gas is to turn the AC on then short out the connector that goes to the low side.

Can't say why the fan isn't running in that position. You need the schematic to figure out if it's a bad switch.

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Reply to
DougW

Even with no compressor, you should get the fan running. I would check the fuses first thing. Once you get a fan, you likely will still not get the compressor to run if it has been sitting for a long time w/o running (which it sounds like it has).

I did the R-12 to R134a conversion on my '88 MJ last summer - no way I was driving that thing to Texas in August with no A/C. In my case, I had a known leak around the end cap so I elected to replace all the seals in the compressor as well as all the o-rings on the hoses and the shaft seal. The recommended way to convert the old compressors is to replace the receiver/dryer at the same time so the whole shooting match cost me right at $50 - including the refrigerant - and took 4-5 hours of work. I slightly over filled it and the darned thing made a 3500 mile trip in the Texas heat and is still just overfull - no leaks, lots of cold air. With the ambient temp at 19 degrees right now, the latter doesn't signify much ;-)

Plan on a rebuild. You'll need to do some research on how to do that but you basically need a decent set of tools including a good set of snap ring pliers. Contact me about parts and instruction sources if you feel like tackling the job. Local shops wanted $800 - $1000 to fix it for me but they insisted on a new compressor so I figured $50 was a good bet.

Reply to
Will Honea

This is an excuse to buy toys! Get at least the "Basic Service Training Manual" before you do anything else. These parts and tools should be available locally too. I overhauled the AC in my 1987 Suburban myself, after taking it to three shops. None of them was smart enough to drop the shroud around the rear AC to check for leaks there, or maybe they were just lazy.

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You will need a vacuum pump if the system has a leak or still has R12 in it. It is almost certain that one or both is true. You don't really need a charging station. Just don't "knowingly" release refrigerant into the atmosphere. If you contemplate switching to R134a then you really do need to replace all the seals and O-rings like Will says.

Could be a fuse too.

Earle

Reply to
Earle Horton

Just to give a feel for the "toys", you can get a pretty good manifold gauge set for $29.99 and a usable-for-home vacuum pump for about $30 at Harbor Freight - or take one of the cheapy compressors and use it in reverse to evacuate the system. Either pump will get you down to under 27" hg - perfectly adequate for home use. I bought a case of R-134 at Sam's for $28. Get at least one can of R-134 with dye in it to check for leaks.

Then study the manual well before you start. At that age, budget for new hoses, too. That's probably the most age-sensitive piece after the o-rings and seals. Read, learn, then re-read the safety stuff in the manual - R-134 (or any refrigerant) can ruin your whole day.

Reply to
Will Honea

If your AC is undamaged apart from a fuse and otherwise working correctly, there is also no compelling reason to switch to R134a since R12 is still legal to use and is legally available although expensive. For $20 you can take the on-line open book exam to get an (immediate) EPA Section 609 MVAC Tech Certification number which enables you to buy refrigerant (R12 is available on ebay).

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You didn't mention whether or not switching on the AC activates the AC compressor clutch. If not, it is likely the fuse since both the AC switch and the blower motor fan are on the same 25 amp fuse (fuse # 6 labeled FAN/HTR).

If replacing the fuse causes the compressor clutch to cycle, you may be able to figure out whether or not your AC still contains any refrigerant either by seeing bubbles in the sight glass located on top of the right wheel well in the engine compartment or by using gauges. If there are continuous bubbles (rather than just an initial stream when the AC compressor clutch engages) then the system is low on refrigerant. If you see nothing then the system is empty and there is a leak. You may be able to identify it by seeing mineral oil stains on the lines or condenser. If the leak is in a line and the compressor is functional, replacing the line and the receiver-dryer and evacuating and recharging with R12 may be the best option.

The pros of switching to R134a are that it is cheap and readily available.

The cons are that a retrofit done correctly is time consuming, and requires complete flushing and removal of ALL of the R12 and mineral oil. PAG oil (used with R134a) is not compatible with mineral oil, and also, if there is any residual R12, the chlorine in the R12 will cause the PAG oil to deteriorate and lose its lubricant properties eventually causing catastrophic damage to the system ("Black Death"). Ester oil is preferred in a retrofit for these reasons.

Another con is that, although some systems cool equally well with a R134a retrofit, Grand Wagoneers reportedly do not. Changing to a parallel flow condenser can increase the efficiency, but this requires custom work since there is no drop-in parallel flow condenser replacement available.

Also, one poster mentioned overfilling with R134a. The general recommendation is to only fill to 85-90% of the R12 specification. Your 1989 GW specifies 32 ounces of R12, so R134a would be about 28 ounces. The Chrysler retrofit recommendation however was for only 26 ounces. The reason for the conservative number is likely because R134a raises compressor discharge pressures, particularly in high ambient temperatures. Overfill can cause high pressures leading to unexpected and sudden rupture of compressor discharge lines.

Reply to
Apple2Steward

Good info above! My overfill was about 1 oz when I added esther oil with dye to check for leaks and I had to bleed some off to keep the head pressure below 250.

I bought a manifold gauge set just because of that head pressure issue and flushed everything as described. Side note: since I needed wheels while working on the compressor, I picked up a compressor from the junk yard and threw it in as an idler while the waiting for parts and such. Out of a dozen or so compressors in the yard only a couple even turned smoothly enough for that so I would have little confidence in a used part. In fact, you might save some wasted effort by putting a wrench on the shaft nut of the compressor you have and seeing if the shaft turns smoothly. It may not feel too good at first - the oil congeals on some parts inside the compressor - but it should turn without any noticeable rough spots. If it doesn't, all this may be wasted effort.

Reply to
Will Honea

Thanks very much--this is all info I wasn't aware of. I'll check all fuses and sensors with meter and then proceed. I'm sure that aside from all the electrical questions, the freon is long gone, and I will need to find a local R-12 capable shop.

Thanks again!

Reply to
randallbrink

I'll do it. Checking the fuses sounds like the kind of no-brainer thing I should have done already, but as you know, the GW fuse boxes were engineered long before the vehicle developed the way it ultimately did, and in the last few model years, the fuse box is completely blocked from view and practically inaccessible, due to the factory air conditioner vents. Nevertheless, I will check the A/C fuse(s) and hope that it's as simple as that, plus, the system will doubtless need to be charged with R-12.

I do not want to switch to 134a. I did that in my Mercedes 300D, and was never so disappointed in how warm the "air conditioned" air was-- no noticeble cooling from ambient. They can keep R134a as far as I'm concerned. R-12 is readily available hereabout or on eBay.

Thanks very much.

Reply to
randallbrink

This is very encouraging. I don't mind the work, or the studying up for the project, or any new tools--just do not want to pay the usual exorbitant shop prices for anything having to do with Air Conditioning. I may or may not need a compressor, but probably do need to rebuild mine. I would also like to replace all seals and hoses at the time of the job, to avoid having to back there later on.

I'll research what my stock system consists of and get back with specifics.

Thanks very much for the advice and the offer of further help.

Reply to
randallbrink

Very good information, indeed, and thank you. I will inspect accordingly, but am doubtful that the fuse is the culprit, as from your description, the fuse is the same as the Heater fan, which currently works fine. I was hoping that the primary problem was a fuse, and the system would simply need charging with R-12.

I do not want to convert to 134a, as I have never been happy with this conversion in the past, and have never known anyone to be pleased with it, primarily because the R134a will not cool like R12, and for the huge cabin volume of the Grand Wagoneer, this is likely to be an even bigger consideration than in passenger cars, where I have experienced the low/no cooling of R134a on the past.

Reply to
randallbrink

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Very good information, indeed, and thank you. I will inspect accordingly, but am doubtful that the fuse is the culprit, as from your description, the fuse is the same as the Heater fan, which currently works fine. I was hoping that the primary problem was a fuse, and the system would simply need charging with R-12.

I do not want to convert to 134a, as I have never been happy with this conversion in the past, and have never known anyone to be pleased with it, primarily because the R134a will not cool like R12, and for the huge cabin volume of the Grand Wagoneer, this is likely to be an even bigger consideration than in passenger cars, where I have experienced the low/no cooling of R134a on the past.

---- ----- ---- R134a wasn't too bad in the Suburban, and talk about huge cabin volume. I am assuming that if there is a leak, it is all gone by now. I have found that to be a good assumption in the past.

Earle

Reply to
Earle Horton

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