A/C clutch replacement, 740

[jimb]

Good day,

I recently purchased a 1990 740 B320FT (number 3 in my stable of
740's)

A/C has (in theory) been properly converted from R12 to R134A. Port
has been installed.

Pulley on compressor doesn't turn but apparently shaft does. What's
with that? Can the clutch spin in the compressor housing independant
of the shaft?

I assume this is a magnetic clutch- apply power and it grabs the
compressor shaft.

Belt (I believe) broke. It's gone for the most part but I found a few
pieces of it.

Freon is apparently gone.

I am trying to understand the Brickboard FAQ with little success.

If it is a clutch, do I need special tools to replace it?

Is it a B I zitchy job?

Better a rebuilt compressor?

TIA

jimB

 

[James Sweet]

Good day,

I recently purchased a 1990 740 B320FT (number 3 in my stable of
740's)

A/C has (in theory) been properly converted from R12 to R134A. Port
has been installed.

Pulley on compressor doesn't turn but apparently shaft does. What's
with that? Can the clutch spin in the compressor housing independant
of the shaft?

I assume this is a magnetic clutch- apply power and it grabs the
compressor shaft.

Belt (I believe) broke. It's gone for the most part but I found a few
pieces of it.

Freon is apparently gone.

I am trying to understand the Brickboard FAQ with little success.

If it is a clutch, do I need special tools to replace it?

Is it a B I zitchy job?

Better a rebuilt compressor?

TIA

jimB

I'm a little confused by your post. I've seen AC clutches fail in two
ways. In one, the outer pulley spins by the drive belt, but the clutch
will not engage and drive the compressor. Another failure I saw, the
clutch seized up and was spinning the compressor even though it was not
supposed to be. In that case, the compressor was dry, seized up, and
burned up the belt.

If the refrigerant is already gone, I would lean towards replacing the
whole compressor rather than just the clutch, it's worth checking, but
the cost difference may not be all that great. Either way, I recommend
you replace the shaft seal on the compressor while you have the clutch out.

Be sure to replace the filter/dryer before having the system charged.
Replace the pressostat on that as well. Honestly, I would go through and
replace all the seals, inspect the hoses, and flush out the system with
solvent. You never know how well the conversion job was done by someone
else, and any of the old oil left in the system will break down in the
presence of R134 and make a real mess of things.

 

[jimb]

I'm a little confused by your post. I've seen AC clutches fail in two

Me too, car is not here now so I can't look at it. I can't figure out

If the refrigerant is already gone, I would lean towards replacing the
whole compressor rather than just the clutch, it's worth checking, but
the cost difference may not be all that great.

Point taken, I am checking on rebuilt now. Clutch is $170 +/- at FCP.

Be sure to replace the filter/dryer before having the system charged.
Replace the pressostat on that as well. Honestly, I would go through and
replace all the seals, inspect the hoses, and flush out the system with
solvent. You never know how well the conversion job was done by someone
else, and any of the old oil left in the system will break down in the
presence of R134 and make a real mess of things.

Points taken.

I have most of the documentaion on this car, I need to go through and
see who did the conversion and when. Most likely dealer though.

I wouldn't normally bother but car is really nice and the A/C working
would be good.

cheers

jimB

 

[James Sweet]

I have most of the documentaion on this car, I need to go through and
see who did the conversion and when. Most likely dealer though.

I wouldn't normally bother but car is really nice and the A/C working
would be good.

cheers

jimB

There's also the option of a junkyard compressor, depending on the
weather in your region, they may not be too heavily used.

I fix the AC on any car I drive, it's nice to have, and it's really not
all that hard to do. If nothing else, it makes the defrost work so much
better in the winter.