BigBlock73

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25 years ago I had my A/C system removed and replaced with the non A/C stuff (foolish youth with the go fast bug)

I had the shop do this while the engine was out getting some modifications.

Now that I'm older and wiser ( ? ) I want to put the A/C back in.Going to be 99* here tomorrow.

I saved everything that was removed.

The "suitcase" was swapped out as well.

My question is,does the engine need to come out to reinstall the complete system ?

Will be doing this as my winter project and want to start the planning stage now.

sofakingdom

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Yeah I feel ya about the "wiser" thing...

No. (thank goodness)

In fact, it's actually possible to assemble the entire thing outside the vehicle, and drop it in that way. You could theoretically even charge it up that way if you had the right eqpt.

Hint: go visit a vehicle assembly plant that offers tours sometime.

I STRONGLY recommend replacing EVERY PIECE of rubber in it, including the O-rings; along with a new compressor, new accumulator/dryer, and new Frod red/orange orifice tube. (96 Crown Vic will get the right part) Flush every metal part you intend to re-use (metal line sections, evap, & cond) with some sort of NON-RESIDUE solvent such as acetone, lacquer thinner, MEK, denatured alcohol, or actual AC flush; NOT paint thinner, turpentine, mineral spirits, brake cleaner. Pour a bit into the part and blow it through with compressed air and a white rag over the other end; repeat until the solvent comes out ABSOLUTELY CLEAN. Then assemble, evacuate, and charge with R-134A instead of 12.

Make sure your cooling system works PERFECTLY. Remember, the AC doesn't "generate cold"; it MOVES HEAT. Specifically, it moves it from the air flowing over the evap, to the cond, where it must then be expelled into the ambient, into the air flowing through the cond & rad. All at the same time as the engine and transmission are also trying to get rid of waste heat. Gotta make sure the whole system for doing that is performing at its best.

BigBlock73

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Really happy to hear the engine doesn't need to come out.
I'll be pulling everything out of storage.

Will definitely be having many more question.

Thanks for the advice

BigBlock73

iTrader: (1)

Was reading other post about A/C and saw this on one of them.

https://www.ebay.com/itm/360772642508?rmvSB=true

And this one for stock replacement

https://www.ebay.com/itm/New-OEM-Gen....c100005.m1851

Is the new designed compressor a better choice than the old GM one ?

sofakingdom

iTrader: (1)

Yes. The old GM compressors were terrible, by modern standards. The newer ones are better in every way.

WILL85IROC

mine was ripped out also, I will be putting bk in this winter too, thnx for the info...

BigBlock73

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sofakingdom
I appreciate your time and advice.

Is that kit from Classic Auto Air good or are there better options?

sofakingdom

iTrader: (1)

Can't say, never used it. (or any other) I've just hated dealing with the old crappy GM compressors since... forever. They're right up there with their starters in my opinion; Stone Age relics that they hung onto and didn't improve, or even fix the stuff that ALWAYS went wrong with about ALL of them or ways that they were simply inferior once it became apparent after they had been in use for a few years, for WAY too long.

bluegrassz

iTrader: (3)

You might consider a aftermarket under dash unit. You will have to do some fab work because a direct bolt-in is not available. You can find a few install post on here.
I think I may go with something like Vintage Air.

sofakingdom

iTrader: (1)

I suspect there might be a reason no bolt-in under-dash units are available... But could be something worth a look, anyway, esp if your interior stuff for the HVAC system is molested beyond recall.

bluegrassz

iTrader: (3)

I had done the same thing removing all my ac. Now I am older and thinking " Why did I do that?"

Going through or sourcing all the factory parts and retrofitting for r134a is good and all. But at the end of the day, you still have the ugly HV/AC box under the hood.
Either way it will be some work. It all depends on if you want a "stockish" look with factory parts, or if you want a "cleaner" look under the hood. Not to mention replacing the factory heater core is a big pain in itself.

BigBlock73

iTrader: (1)

I recently replaced the heater core and can't imagine a aftermarket unit fitting under the dash.

I removed the complete A/C unit with 23k on it and now have 27k miles.
I saved every piece that was removed.
Under dash is almost new condition.

I want to keep it stock ish but updated

bluegrassz

iTrader: (3)

That being the case, I would just reinstall everything also.

BigBlock73

iTrader: (1)

I pulled it all out and I was surprised to find a bag of the cut off connectors.
I had thought they tucked them were they could.
I'm going to try and find where the cut wires in the harness are.

Might need some help and pics.

sofakingdom

iTrader: (1)

The ENTIRE HVAC harness is just ONE BIG thing. Vacuum lines and all. Comes RIGHT OUT as a unit. Has a rubber grommet where it goes through the firewall to make it even eeeeeeezier.

Don't know for sure; but I'd be willing to bet that LOTS of other GM cars from around the same years are COMPLETELY interchangeable, making junk ones EEEEEEEZY to come by. Late 80s Caprice would be the first choice of eligible candidates.

One plug under the dash unplugs it from power. One vacuum source plug under the hood provides it with vacuum. One large red wire connects to the hard battery feed for the blower high speed. Everything else it plugs into, electric or vacuum, is part of itself. (control head, compressor, blower motor, heater control valve if your car has that) It's just ... 2 eeeeeeezy.

BigBlock73

iTrader: (1)

Glad to hear it's an easy reinstall.

In the bag were the connectors cut from the wiring harness.

I have the connectors for the:
accumulator
Fan
Compressor
Pressure switch ?

The wires left in the harness were made so that I can't see them.
I would like to keep from having to dig into the harness any further that I have to find them.

I've been searching for pictures and have found a few.
They should help but until I get some time to start digging,I can only do searches and ask questions.

sofakingdom

iTrader: (1)

That's why I'd recommend an unmolested one... no digging required. All one piece, ready to just plug in.

If you pop the control head out, then the console, then the floor heater ducts, you'll see how EEEEEEZY it iz to just swap out the whole thing. Once you'll see it you'll kick yourself in the butt for ever even THINKING you had to actually do any work.

BigBlock73

iTrader: (1)

After searching the internet and looking at all the pictures of the A/C wiring in the engine bay,I was able to find all the wires neatly tucked into the harness.

The compressor has 2 connectors,each has 2 wires going to it.
The forward connector has Black and Green wires.The rear connector has Blue and Green wires.
The wires coming out of the harness are Black,Blue and 2 Green.
I've been looking for a A/C wiring diagram but haven't found one .

Are the 2 Green wires both ground and are interchangeable ??

sofakingdom

iTrader: (1)

The green wires are power to the compressor.

In a car, ground wires are usually black.

Compressors usually have 2 connectors. One has 2 pins, wires are green and black, with a diode across them with its cathode (end with stripe) on the green and anode on the black.

This black wire then is usually short (12" or thereabouts) and usually goes to a thing with a single terminal on the back of the compressor. The thing in question is the high-pressure cutoff switch. The switch body is ground: when its limit setting is exceeded (an over-pressure condition) the switch opens, shutting off the compressor by ungrounding the normally grounded end of the clutch coil winding.

The usual AC wiring (for the compressor) is: green wire from under the dash through the rubber grommet, to the low pressure cutoff (on the accumulator); 2 green wires from there, one to the compressor and one to the ECM (so it knows whether the compressor is being told to run and not cycled off by the LP sw); the green wire is the one described above.

Not sure about a blue wire. Never seen any such at a GM AC compressor. Photos of the connectors, showing the wires and the locations that they break out of the harness, would help.

There are a number of other wires coming through the grommet through the firewall that go to the blower resistor, along with one that goes to the blower high-speed relay. Can't recall the colors but it seems like there's a blue, yellow, orange, brown maybe. One will go to the relay connector, and there will also be a small black wire to ground, a thick purple wire to the blower, and a fat red wire that picks up hard battery for the blower high-speed feed at that connector. The blower motor will have a fat black ground.

There are usually either 1 or 2 vacuum lines included in the harness. One of them (white) feeds vacuum to the little valve thing that controls the air doors in the interior; the other (purple), if equipped, goes to the heater control valve. Might have the colors backwards, it's been a long time since I worked on one.

That's usually all there is to it. Pretty much a no-brainer.

Again, I recommend just going and getting an unmolested one out of a junk car, so you don't have to puzzle it out. Unplug it from the junk car's control head, compressor, and blower parts; pop the grommet out of the firewall; install it in your car; plug it back in. Way too eeeeeeeeezy and screw-up-proof.

BigBlock73

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BigBlock73

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sofakingdom

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Looks like the diode is inside that heat shrink thing.

Green = power to the compressor
Blue = looks like tells the ECM there's head pressure, turn on the fan

Green to green (all 3), blue to blue, ground the black.

BigBlock73

iTrader: (1)

Thanks
Going to start repairing the connectors

BigBlock73

iTrader: (1)

I got all the wiring figured out and repaired.

I've decided to reinstall everything and see if it'll hold vacuum.Everything looks new, just a little dusty.
I'm going to do the 134a update on the system.
There are a few videos on Youtube detailing the compressor disassembly and reassembly.

Question on removing the clutch.I need to purchase the clutch remover/installer tools and don't know if I have the compressor that requires the SAE and metric tools?

I found this company that seems to have everything I need.
https://www.shopcenturyautoair.com/s..._Products.html

LT1/TA

It have personally taken one of those compressors apart and it is not worth the hassle and time.I would just buy a new one,not rebuilt.
If you do decide to reseal it you will need the puller and installer for the clutch (it is metric),a shaft seal install tool,and you will need to press the outside ring around the compressor off to change the two outside case seals.

BigBlock73

iTrader: (1)

The car had 23K miles on it when the AC system was removed.
I energized the clutch and spun the compressor and it spins fine and can hear the compression.

I've watched multiple videos on disassembling the compressor.
I have a press and know I need to purchase the install/removal tool.
The shaft seal install tool comes with the seal kit.

sofakingdom

iTrader: (1)

I think you can "rent" the tool without having to "purchase" it.

Just the same, I don't think "repairing" that compressor, is going to prove satisfactory, in the long run. (yeah I know, "in the long run we are all dead", but...) R-4s aren't ... all that.

gavin.priestley

sofakingdom

iTrader: (1)

Green should have power on it when the key is on and the AC is on. Gets power from the AC control head via the low-pressure cutoff sw mounted to the accumulator.

Check for 12V at that switch. Should have power on both sides if it's fully charged. If the system has no refrigerant, then that's at least 1 reason why the compressor isn't getting power... the system pressure is too low to operate the LP sw.

gavin.priestley

1989karr

If there is no refrigerant, the system doesn't send power to anything as if you have no refriegerant, youmight not have oil so it prevents the compressor from coming on and frying itself.

In order to see if you get power to the wires, you'll need some refrigerant in the system. About a can to 1.5 cans is usually enough to get the compressor to cycle / signal the compressor to come on. I believe the switch on the accumulator is what tells the ECM that there's pressure in the system.

gavin.priestley

1989karr

hmm, did you try checking the ac compressor relay?


I had a bad one on my truck....so everything was fine but I never got power to the compressor. Its a pretty easy / fast thing to replace!

gavin.priestley

1989karr

If I recall. I THINK the compressor relay was agfainst the driver seide firewall. But I think it depends on what otor you have, but I remember seeing it listed on the HAYNEs wiring diagrams.

sofakingdom

iTrader: (1)

I don't think there's a compressor relay in our cars. No need for it. The compressor is driven right straight off of the "mode" sw in the dash. The green wire goes from there, through the firewall, to the low pressure sw, then from the other side of that sw to the compressor. Very simple.

The high side cutoff sw should NEVER show voltage except when (a) the compressor is running, (b) the wire is hooked up, and (c) the compressor head pressure is above about 400 psi.

You say there's no power, but then talk about the compressor "building pressure".

With the compressor NOT running, there should be something on the order of 100 psi in the system, both sides, if there's any significant amount of refrigerant at all in the system. When the compressor runs, it should rapidly drop to around 40 on the low side, and rise to 250ish on the high side. The low pressure cutoff should kill it when the low side gets down to 25 or so.

What were your pressures? Was the compressor running?

OrangeBird

iTrader: (1)

Interestingly , in 1988 all 8 cyl cars had no relay , just as sofa says the compressor clutch is driven straight off of the control head , through the pressure switch . But the 6 cyl cars , VIN "S" on this diagram , do have a relay driving the compressor clutch .

sofakingdom

iTrader: (1)

Yeah there's a connection to the ECM that turns it off; the 6-cyl cars evidently needed a way to disable the AC when the car was supposed to move... otherwise there wouldn't be enough horsepucker available. Both of em would have been consumed trying to compress Freon.

I've never touched or worked on a 6-cyl one of these cars though, under the hood. Never really even seen one. I think I've run across some in junkyards but I've always averted my eyes. I DID look at a 4-cyl one once though; just like it's real hard not to look when you come across someone with a horrific injury or something, it was so ... morbidly ... stomach-turning ... that I couldn't help it. I regret it to this day. It was ... disturbing. Now I can't unsee it.

1989karr

I got a 6 lol I can;t imagine how horrible the 4s mst have been!!!!