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91 Jeep Cherokee How to Pull Vacuum

4K views 37 replies 5 participants last post by  fhorta 
#1 ·
I have just replaced a bad condenser on jeep and in process now of pulling vacuum before refilling condenser oil and putting freon in.

I have manifold gauges blue hose on low side and red on high side with yellow to vacuum pump. I am getting no vacuum at all. Left overnight and nothing.

Oil level on vacuum pump is above the halfway full mark actually almost to full. It's brand new. If I take hoses out I feel suction on finger, just nothing if i connect. Also, nothing goes into low side and nothing comes out. I tried pumping compressed air into it but its like closed off. or something. It does have the retrofit R134 valves on low and high ports. Also no suction through low side neither. It's a 91 jeep so not sure if that's the years design how the compressor operates. I have seen videos mainly on 95's ac compressors how to charge, fill with oil and pull vacuum but this one seems to be different. Ideas. Suggestions please. Thanks
 
#27 ·
Yea mine are positioned on the back of compressor. I bought new ones and came with whole back assembly. Not leaking anymore. The next leak came from around the back head plate. I was tightening at 27 lbs psi per youtube video instructions, but was still leaking. I gradually incresased tightness all the way to 60 lbs psi and finally sealed. It is now holding air pressure and holding vacuum.
 
#32 ·
Awesome, thank you. I will check that. ​​​​​​​I have put 2 cans of freon. Cans say they have a net weight of 12 ounces. Compressor originally takes 2.38 lbs of R12. According to a chart, that is equivalent to 2 lbs of R134A. I am coming up with 36 ounces of R 134A of freon to charge compressor. So I would need another can.* Is that about right? When I weighed full can, I got .75lbs
 
#33 ·
Ok so that component is not there. There is no ball or lines. Thinking about opening foot well area and see what's in there by firewall. But if this component you mention is missing, will there be anything else im firewall area that will fix problem? Thanks
 
#34 ·
Does it have the stock bumper? People who remove or replace the stock with a custom usually relocate the ball to somewhere inside the engine compartment. That reservoir also serves the cruise control (if you have that).
 
#35 ·
It looks like it has cruise control but never used it. Anyways, looks like problem solved. There was a loose little tubing coming out of firewall into engine bay. Stuck it back in to little boot which is attached to drip system irrigation looking thing with more tubings. Now blowing through vents.

Otherthing now is fluttering sound from ac compressor . it's intermittent sound. I put more tension on belt and sound went away. But when i rev engine, after i let go of gas ac hesitates like it wants to turno off but then when engine idles normally again, ac system back to normal. Maybe tension belt some more?
 
#36 ·
Don't just keep tightening the belt without measuring the tension. I ruined a perfectly good clutch bearing that way. No matter how much I tightened it the belt squealed. Turned out the belt was a POS and I over-tightened it and the bearing failed. Now I use a tension gauge.
 
#37 ·
What Fourspeedman said.
I use this:

https://www.amazon.com/Gates-91132-Belt-Tension-Tester/dp/B000CRDLZM

I found that the "Yeah that looks about right" method does not work with my '00.
Worked fine in my '96 though. LOL.
180-200 lbs for a new belt. 140-160 for an old one.
I always use the low end of the specs.
When I first got my gauge I did the "Yeah that looks about right" method.
Twist the belt, 1/2" of play, you guys know the routine.
It only registered 100lbs on the gauge so.....
 
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