Truck's AC units-a-knockin

[CN Spots]

I just had the old AC in my '92 C1500 V6 switched over to the new stuff a few months ago, seemed fine at first but here lately it's been knocking something awful. Is this normal when they switch freon? It's cooling as well as it ever did, just sounds like its coming apart.


spots

 

[Reel Poor]

Re: Truck's AC units-a-knockin

Do you know how the conversion was done, professionally, or with a kit form the parts store.

No thats not normal. However it is typical it it was not done properly.

 

[puddle jumper]

Re: Truck's AC units-a-knockin

were is the noise coming from
-engine compartment front or rear
-in the dash around the heater motor

 

[CN Spots]

Re: Truck's AC units-a-knockin

It was done by pros (who's to say) at Firestone. The noise seems to be coming from the compressor.

spots

 

[ob]

Re: Truck's AC units-a-knockin

ALL of the mineral oil should have been removed from the sysytem and replaced with ester oil as the R-12 lubricant is not compatible with R134 refigerant.It is also recommended to replace the existing drier as well.Complete evacuation of the system for a minimum of 45 minutes is a must.The final weighed charge will be some 10% less than the original R12 charge to compenstae for the difference in temp/pressure relationship of the R134.Sounds like you either have a overcharge or a lubrication issue. And finally,hopefully you won't experience any "o" ring failures due to the ester oil if they were not replaced.

 

[puddle jumper]

Re: Truck's AC units-a-knockin

i agree with ob