So my air went out on my 91 f150. I bought the kit from autozone and the retrofit kit with the fittings. This is probably a stupid question but which port is the low pressure port? I'm thinking it is the port on the passenger side because thats the only port the low pressure fitting fits on duh. Before I started tinkering with it the guy at autozone told me the port on the driver side was the low pressure so I pulled the valve stem out so I could fit the retrofit fittings. Come to find out the fitting was the wrong one and now my high pressure port doesnt have a valve stem in it (and i broke it when I was pulling it out) Can I buy just a valve stem somewhere or am I going to have to replace the whole assembly? As always thanks in advance.

 

Yes any auto parts place should have one.



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Awesome! This is exactly what I needed! Now only if I could get ahold of all of the other diagrams just like this for the entire engine compartment so I know exactly where everything is. Where did this diagram come from?

 

The diagram came from the Ford shop manual.
You can buy them at Helminc.

 

I hate to burst your bubble but those so-called retrofit kits very well may cost more money in the long run. It is a well known FACT the oils used in R-12 systems and R-134a are not compatible. The mineral oil used in R-12 systems hold residual chlorine from the refrigerant, when you introduce PAG or ester oil along with the R-134a bad things can happen.

I highly suggest to explore drop in replacements such as Freeze 12, Duracool, AutoFrost, etc. instead of of those cheap-a** kits at the retail stores. They work much better without the potential for causing catastrophic failure as a half-a**ed R-134a conversion.

But hey, it's only money.....

 

Actually, I would suggest doing the conversion correctly by flushing the system and adding back the correct oil.
Those "drop in replacements" (there's really no such thing) are just as bad as the cheap-a**ed kits. Each one of them has their own laundry list of potential issues too.
The only one I would even think about recommending is Freeze12, but that would only be if an alternate was absolutely necessary. It's far from a be-all, end-all, and not a "drop in" either.

 

I guess we can agree to disagree on replacement refrigerants. I have used AutoFrost successfully in several vehicles for the last 7 years. I have experienced no increase in vent temperatures or much differences in pressures from R-12. You are correct to do the job right does require a flushing regardless of which refrigerant you choose.

The last vehicle I put AutoFrost in, my current '92 F-350, I did a cheap and dirty style fill after replacing the condenser after the output fitting cracked. I replaced the receiver/driver, various 0-rings, pulled a vacuum for 90 minutes, verified it held a vacuum for over 2 hours then filled it with AutoFrost. So far so good, never did do a flush just to see what happens. I might get lucky!