AC help.

[blazinzuk]

So where do I start. How do I diagnose. This is in my 89 burb. Serpentine belt big block. Uses the flat ac compressor I believe it's called an R4.

No obvious leaks. No obvious damage.

Clutch on the AC compressor does not switch on.

We have a trip in June where there's a good chance it will be very warm and I need to take the burb.

Happy wife happy life is what this is all about

 

[Fastereddie]

Could be low on freon, even though you don’t see the leak. You could try jumping out the low pressure switch to see if the compressor kicks on

 

[frankin5]

A set of gauges and a paper clip. Has it been converted to R134 or still original?

 

[AgDieseler]

Hard to tell without gauges, but the clutch is engaged by pressure, which is controlled by Freon weight in the system. Freon without dye isn’t really visible when it leaks, though most oil contains a dye.

David

 

[H20 Toie]

Jump the low pressure switch
If it works then all you need to do is add Freon

 

[blazinzuk]

Could be low on freon, even though you don’t see the leak. You could try jumping out the low pressure switch to see if the compressor kicks on

Jump the low pressure switch
If it works then all you need to do is add Freon

How pray tell do I jump the low pressure switch? I have never done AC stuff before. Well except removal

 

[Fastereddie]

Unplug that and put a piece of wire in the plug.
That is the low pressure sensor. When froen gets low it prevents the compressor from kicking on.

 

[blazinzuk]

A set of gauges and a paper clip. Has it been converted to R134 or still original?

It is still R12

 

[frankin5]

Ouch!! That stuff is expensive. Front and rear air?

 

[blazinzuk]

Ouch!! That stuff is expensive. Front and rear air?

Yep

Need a fan for the rear air too. That's 70 bucks

 

[frankin5]

How long ago did it blow cold air? Start with hot wiring the clutch and see if all works. At that point you will need a set of gauges to continue diagnosis. Rent for free at Auto Parts store maybe. That system has close to 20 "O" rings that could be weeping. The compressor seal could be weeping. hope it is not the rear evaporator. I have rear air in my blazer and I have a spare rear unit for that reason. Every trip to salvage yard I look for Subs for spare parts to the rear air.

 

[kgblazerfive]

They make inexpensive stuff that will work with R12 Freon. Converting it is not all that bad... sort of.

Check the switch see if the compressor turns on. If it does fill it with a filler kit that will work with R12 make sure it has tons of dye and pray it doesn't leak out of the rear unit.

 

[blazer74]

You could check the A/C fuse first.

 

[frankin5]

We all assume that was done.