81 Rabbit diesel A/C Issues

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backwoods - 21 Dec 2006 04:22 GMT

I'm halfway through the long process of bringing back an 81 Rabbit
diesel from the nearly-dead. It has A/C, though I'm not certain it is
original since the control on the inside, a rotary switch affair, seems
patched in. Anyway, the compressor turns but seems too stiff - caused
the belts to squeal back when I tested it, before starting teardown
work (can't run it right now).

I'd love to have working A/C but don't have much money. I see seal kits
for converting to R-134a. If some of these seals go into the
compressor, it seems I'd have little to lose trying to install them,
maybe in the process I can free up the stiff compressor. But I can't
find any decent instructions for disassembly/reassembly of the
compressor. If I can't rescue the old compressor, it won't cost more to
get a rebuilt one whether I try digging into it or not. Even rebuilts
are serious money :-/.

So has anyone worked on a compressor and is there decent instruction on
the net? My Bentley manual says nothing.

An aside, anyone know an economical source for the cold-start cable?
The cheapest I can find is $40 X-(.

Tony

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Jo Bo - 21 Dec 2006 23:18 GMT

I added a AC on a 78 diesel and can tell you first hand it will never work
right. They were originally added on the diesels but the newer ones from PA
had it put on at the factory but still problems. You will have bracket and
belt problems you would not believe. When the A2 body type came around in 85
they mounted the compressor and alternator along with a power steering pump
much better. VW bought a aftermarket ac company in Texas and used their
brackets and was very slow to move away from them.

JoBo

> I'm halfway through the long process of bringing back an 81 Rabbit
> diesel from the nearly-dead. It has A/C, though I'm not certain it is
[quoted text clipped - 19 lines]
>
> Tony

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backwoods - 23 Dec 2006 03:43 GMT

Thanks for the info JoBo. I guess I should look carefully at the
brackets and pulley alignments before doing anything else with the
existing AC. The alternator belt was broken when I got the car, so I've
got to loosen the compressor and remove its belts in order to replace
the alternator belt. Does the compressor bracket tend to get bent or
work loose or such? Mine has no PS.

It's a little hard to see into the pulleys area, but at first glance
it looks like what the manual shows for brackets & belts. There's
nothing odd inside the cabin, except for the rotary control ... the
evaporator housing & such looks like what the manual shows. I'm a tad
puzzled by the mix of proper & unusual on this beast. The car is new to
me.

The Bentley manual says precious little about the AC control system.
I'm guessing there have to be some extra relays and such somewhere to
turn the compressor and the radiator fan on & off according to the
thermostat. I'm also guessing that the rotary control tacked into the
dash is a thermostat adjustment.

> I added a AC on a 78 diesel and can tell you first hand it will never work
> right. They were originally added on the diesels but the newer ones from PA
[quoted text clipped - 3 lines]
> much better. VW bought a aftermarket ac company in Texas and used their
> brackets and was very slow to move away from them.

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Rich - 06 Jan 2007 07:11 GMT

I have an 82 diesel, dealer installed AC. The main v-belt drives
the water pump and AC compressor which has two pulleys. A second
thinner shorter v-belt drives from the compressor to the alternator
mounted on the top. Alternator alignment, belt wearing big problems.
Motorola lasts ~80k, Bosch ~50k from the vibration. Got a second
Motorola and switch them off, rebuilding other for a next failure.
My coaxial control works 3speed blower also temperature adjust that
triggers compressor directly. Radiator fan relay is part of normal
car, but AC switch on now causes radiator fan to run continuously.
Shop says I got DFW compressor (texas). 310k and counting. rich

> Thanks for the info JoBo. I guess I should look carefully at the
> brackets and pulley alignments before doing anything else with the
[quoted text clipped - 23 lines]
> > much better. VW bought a aftermarket ac company in Texas and used their
> > brackets and was very slow to move away from them.

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backwoods - 07 Jan 2007 02:55 GMT

Thanks Rich. What you're describing for belting arrangement is exactly
what I've got. I haven't played with the A/C control in the dash, but
it appears to be just one knob. The regular heater control seems to
still take care of the blower speed, but I didn't get a chance to toy
with it before teardown. Thanks for the heads-up about the alternator.
I'm guessing what you're talking about for rebuild is that the bearings
fail due to vibration? I'd best hunt up a backup before I put her back
on the road. It is a Texas car, so maybe the Texas dealer put in the
A/C. 310K is majorly impressive, so I have high hopes now LOL. My beast
has a bit more miles, but was towed behind a motorhome a lot of the
time, so engine miles are hopefully a good bit less.

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dieselmech - 14 Jan 2007 06:25 GMT

Hello, I had three A-1 VW’s, the truck was rear ended, I have a 1979
rabbit, and 1984 Jetta, both factory AC brackets and such, I do AC a
lot.
A stiff compressor could be the bearings inside, or the clutch
bearing.
I am not trying to insult you, I don’t know what you were turning
I am guessing, I have not seen a VW compressor apart.
I have taking apart other compressors. some I needed to show customers
why the AC failed. broken vanes or bad discharge spring plate
one very big tip. do not overtighten the timing belt, you will destroy
the diesel fuel pump, it has no bearing, the housing is the shaft
bearing.
also do not overtighten the water pump belt, same deal aluminum
housing is the bearing race for the shaft. maybe you knew that.

there are R 12 freon replacements, R 134a is ok but you cannot have R
12 oil anywhere in the evap, condensor or compressor. yes you could
purge the system with acetone, but why.
talk to a AC guy or look up freeze 12 or google search R 12
replacement
I would keep the R 12 set up, R 134a has different operating pressures
also only charge the system 75% of total charge capicity, or you could
blow the condensor apart.

yes the belts need constant adjustments, but I like AC
I like A-1 diesels Both are Turbo Diesels, I run 25% veggie oil
I don’t like the engine noise, but enjoy the 50 MPG.

> I'm halfway through the long process of bringing back an 81
> Rabbit
[quoted text clipped - 31 lines]
>
> Tony

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Bryan K. Walton - 14 Jan 2007 20:52 GMT

Thanks for the explanation guys. Its nice to know that the A/C coming
on with the defroster is simply to make the defrostting/defogging work
more efficiently.

Cheers,
Bryan

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