AC compressor rebuild
03-23-2012, 11:08 AM
#16
Good information. What are the chances that my head gaskets are the problem. It is a very big leak as I try to fill it. I can actually see the green slime oozing out. Likely main head gasket right? Is there anyway to make one?
03-23-2012, 12:38 PM
#17
Rennlist Member
Not likely, according to the literature I could find out there on the interwebz the head gaskets are "rubber coated metal gasket" and they fail like any other gasket. Do you know exactly where refrigerant is leaking from? On my 968 the refrigerant is leaking around the center axis of the compressor and the nose seal. I just haven't had the time to order the kit and start pulling everything apart.
03-24-2012, 11:34 AM
#18
You can get a 944/968 to blow cold air with R134a, with a stock compressor or the Kuehl, if you evacuate and charge correctly, however if you are in a very hot climate constantly you can also upgrade your condenser if needed.
There are several reasons for a compressor nose seal to blow, such as when it is old, there is rust on the shaft, overcharging or failed condenser blower fan motor or problem with its circuit. There are several posts on Renn or Pelican on replacing o-rings and seals.
The more common problem with a factory compressor failing in terms of "leaks" is the nose seal and then the case seal o-rings. As time moves on the pistons, their bores and the wobble plate wear (there are no rings or cylinder sleeves in a post 85/1 compressor), hence to 'rebuild' the bores (jig grind, jig bore, or hone the case bores and get matching pistons) is rather timely and expensive.
When a compressor clutch fries or burns up the coil its usually related to excessive heat migrating from the compressor (due to high friction or pressures) to the coil, by the time that happens chances are the entire compressor is near overdone toast.
While you inspecting the compressor you might as well inspect the compressor to condenser hose, they typically fail over time.
Don't forget to replace your drier, system connection o-rings between the components.
Use the correct refrigerant oil:
Stock R12 systems used 'mineral'.
Stock factory R134a systems used 'PAG'.
Dealerships and some aftermarket shops used 'PAG' when converting from R12 to R134a, others used 'ester'.... we prefer ester because it mixes well with mineral oil.
You can mix ester with mineral oil.
You can't mix common PAG's with mineral or with ester.
So, if you are converting an R12 system to R134a for the first time try ester.
If the system had already been converted to R134a and you are adding more oil you need to determine what kind of oil was previously used (pag or ester).
If the conversion job was done 'right' there should be a blue colored conversion sticker in the engine compartment noting the type of oil, amount of refrigerant, whom did the job and when, otherwise
you would need to research repair orders. If in doubt you would liquid flush the system to remove the questionable oil (another topic).
There are several reasons for a compressor nose seal to blow, such as when it is old, there is rust on the shaft, overcharging or failed condenser blower fan motor or problem with its circuit. There are several posts on Renn or Pelican on replacing o-rings and seals.
The more common problem with a factory compressor failing in terms of "leaks" is the nose seal and then the case seal o-rings. As time moves on the pistons, their bores and the wobble plate wear (there are no rings or cylinder sleeves in a post 85/1 compressor), hence to 'rebuild' the bores (jig grind, jig bore, or hone the case bores and get matching pistons) is rather timely and expensive.
When a compressor clutch fries or burns up the coil its usually related to excessive heat migrating from the compressor (due to high friction or pressures) to the coil, by the time that happens chances are the entire compressor is near overdone toast.
While you inspecting the compressor you might as well inspect the compressor to condenser hose, they typically fail over time.
Don't forget to replace your drier, system connection o-rings between the components.
Use the correct refrigerant oil:
Stock R12 systems used 'mineral'.
Stock factory R134a systems used 'PAG'.
Dealerships and some aftermarket shops used 'PAG' when converting from R12 to R134a, others used 'ester'.... we prefer ester because it mixes well with mineral oil.
You can mix ester with mineral oil.
You can't mix common PAG's with mineral or with ester.
So, if you are converting an R12 system to R134a for the first time try ester.
If the system had already been converted to R134a and you are adding more oil you need to determine what kind of oil was previously used (pag or ester).
If the conversion job was done 'right' there should be a blue colored conversion sticker in the engine compartment noting the type of oil, amount of refrigerant, whom did the job and when, otherwise
you would need to research repair orders. If in doubt you would liquid flush the system to remove the questionable oil (another topic).
