A/C Problems 1992 Tbird 5.0 Plz Help!

[frank3112]

I have a 1992 Tbird 5.0. I have replaced the compressor,low pressure line with accumulator,pressure relief valve on the new compressor,orifice tube,and converted it over to R134a. We put in the correct amount of 134 and oil. Now when the RPM'S go over 2500 the relief valve opens and I lose 134. I was told that I should replace the condensor that it is possible there is a blockage in it that is causing my problem. I tried to blow out the compressor to see if there was a blockage all to no avail. Does anybody have a solution to my problem? Do I need to buy the new condensor? This is my 1st post.. I was just laid off from my job of 18yrs and have to do a lot of the work myself and with a friends help.

[E-bird]

I would look at the oriface and strainer and see if any debris has clogged them. how much 134 did you use to charge the system?
What pressures ( low and high) did you have when finished charging the system at idle?
you did evacuate the system right?

[frank3112]

I did change the orifice. The low pressure side was 50-55. The high pressure was enough to open the relief valve. Yes system was evacuated.

[flewthecoupe]

I don't know if R134 is different than R12 as far as pressures go, but low side should not exceed 25psi and high side should not exceed 210psi. You may be overcharged.

[frank3112]

We only put in 2/12oz cans of 134 and 2oz of oil. The compresser comes with oil in it.

[CDJr]

You say you tried to blow out the compressor, or the CONDENSOR? Before you start replacing more parts, you need to make sure thats the problem. Hook up your gauges again and watch the pressures as you raise the RPMs. If there is a blockage, youll be able to tell. In a diagnostic situation like this, pressures will tell the tale, but only as the engine is revved, not at idle alone. Ill check back afterwhile and see what you found. Hope this helps.

[frank3112]

Thank You, i'll have to wait until Mon. I did all my wife will let me do today.

[Jim Adams]

I have a 1989 Tbird Supercoupe and I trashed the original compressor and this left me with the Fords Dreaded Black syndrome,,not knowing of this I trashed another compressor before I learned,,when you convert on the ford They suggest replacing the accumulator Dryer the liqiud orifice line andthe compressor,,the Condensor they say you can fluch it out with mineral spirits ,,but it has been my experiance that anything other than what is supposed to be in the ford system should not go in it lol the liqiud orifice line on the Tbird has an orifice that a grain of sand would plug it up,,I eventually rep[laced the compressor the dryer the liqiud line the condensor after I learned alot got pissed a hole lot and went threw 2 used compressors 3 liqiud lines 2 dryers all of these where used as I have access to a 500 acre junk yard owned by family but still what a mess it was,,now it works great,,the blow off on the back off the compressor on the tbird blows at 44 lbs I only have 29 lbs on the low side and 200 lbs on high side,,the 134a is not equevilant in pressure or ounces to the r12 there is a conversion chart on line but it is like 16 ounces of R12 is same as 1lb 4 ounces of R134a,,this is real close but to be 100% check the chart.they are a pain in the butt and unlike myself not everyone has access to a junk yard full of parts so you dont want to waiste money,,so do it right the first time on this one there is no room for much error

[frank3112]

I took the car to a friends garage. he's going to try and figure this out. I will keep you all posted, I appreciate everybodys help and suggestions.

[coondawg6]

low side pressure should be between 30 and 40 psi on a 75 degree day and hi side should go about 200 to 225.. doing a conversion to 134a from r12 you will use about 60 percent of your r12 charge but it is totally dependent on pressure readings---thats the most important part when doing a retrofit--you will ALWAYS use LESS 134a than r12...if you are blowing relief valve your probably overcharged but start with basics---1.when a compressor fails debris gets in entire system 2.replace compressor, oriface tube/liquid line, accumulator 3.buy commercially available flush for ac lines(not expensive) and flush condensor (in front of radiator)and evaporator (in dash) until there is no discoloration on a white towel there are no moving parts or valves in these items so unless there is a blockage or a leak fluid should flow with very little resistance. 4. cooling fan should operate effectively and efficiently, without enough air flow through condensor to cool it pressures can rise to 400 psi in a few seconds 5. charge till pressures are correct, dont concentrate too much on volume of refrigerant (although it will always be a less amount than r12) pay attention to pressures -- if all is done correctly you should blow about 51 degrees on a 75 degree day......btw if your low pressure side was 50 and hi side blew relief valve you have a clog in oriface tube liquid line already so be prepared to change, as the oriface tube is the only part that separates the hi side from low side thats where the pressure change is made to produce your cold vapor