Ac blew up on recharge.

[Mattman]

I need to replace the AC system on my 92 F150. It has been off of it since i bought it. I bought new compressor all new lines condenser dryer everything new except evaporator (I flushed and blew it out). Spent most of the day yesterday researching vacuum and charging procedures and thought I had a good idea. I put all the parts on today, pulled a vacuum and it held for 30 minutes. I then pulled vacuum for one hour and got ready to charge. This truck called for 44oz of R12 so I decided to aim for around 32 to 34oz of 134a and pressures on the low side around 37 and 225 on the high side, It is not very hot here today upper 60s with low humidity. It took almost two cans before the compressor would stay on and after I arrived at the desired volume and pressures everything was going well. YES I PURGED THE YELLOW LINE BEFORE EACH CAN. After charging I turned off the truck and let it set for about 5 minutes and started it back up. High side pressure immediately jumped to around 350 or 375 and blew the seals out of my line set before I could shut it off. I don't think anything is messed up because everything is still running now except it doesn't have enough refrigerant in it now and the compressor cycles. So the magic question before I try again tomorrow is, What did I do wrong??? I I don't understand how a system running with 225 high side pressure can go to nearly 400 after shutting it down and restarting 5 min later. Could my problem be a simple as a bad fan clutch? Update!! It will not hold Vacuum now so I fear I blew a seal or the Evaporator out somewhere.

[bohica2xo]

Those pressures are way out of line for an ambient below 70f

You said you installed a new condenser. What brand & type is the replacement part?

Is the fan & shroud installed on this truck?

How much & what type of oil in the system?

.

[Mattman]

Those pressures are way out of line for an ambient below 70f

You said you installed a new condenser. What brand & type is the replacement part?

Is the fan & shroud installed on this truck?

How much & what type of oil in the system?

.

Thank you for your response. All new parts from Napa. Yes the fan shroud is installed. The original R12 system called for 10 oz of oil and 44oz of R12 so I put a total of 9.75oz of pag 46 in it and it had right at 32oz of R134a in it when it went. I was using the following chart as a guide.

http://www.autoacforum.com/download/fil ... view&id=26

I thought I was safe since I had less than 75% of the R12 charge in it. Guess not!

[Mattman]

http://www.autoacforum.com/download/fil ... view&id=27
I have since found this chart which has conflicting information with the one above.

UPDATE! It won't hold vacuum now so I have a big hole somewhere.

[bohica2xo]

Was there oil already in the compressor?

Is this truck a factory A/C unit, or a dealer install? Many 1992 & 1993 F150's actually had dealer installed A/C.

What type of condenser do you have now? OEM was a tube & fin design, some aftermarket stuff is not.

That first chart you posted is a real winner - looks like the old "death kit" package insert. High side pressures over 400 psi...

At 70f ambient & idle, anything past 200 psi is a bad sign.

[Mattman]

Yes there was 3oz of oil already in the compressor. I added 6.75 to the system. In all honesty I really don't know about the AC install. When I bought the truck there was nothing on it but the Evap, Condenser and lines. I made the assumption that since the truck was an XLT model that it was factory installed. The condenser looked the same except it had about twice the tubes in it and they were smaller don't really know how to tell the difference. Thanks for your help. I am going to get this fixed I refuse to be defeated! Any Advice to lead to a successful outcome is appreciated.

"That first chart you posted is a real winner - looks like the old "death kit" package insert. High side pressures over 400 psi..."

Yeah the Internet is a minefield of misinformation, wish I had found this forum BEFORE I started.

[bohica2xo]

Sounds like a piccolo condenser. They have parallel paths, instead of a single pass. They are more efficient, but can hold less refrigerant too.

I have a 1993 F150 with dealer A/C.

Which engine is in your 150? and which compressor model is installed?

Finding the leak is the first order of business. If it won't hold vacuum it may be a bad seal - or an issue with your service fittings / hoses / manifold.

Testing the manifold & hoses is easy enough. Use a 1/4 tube union to join the high & low lines. Connect vacuum to the center port. Open the valves, pull a vacuum & close the valves. Shut the vacuum pump down, & disconnect it. The gauges should hold vacuum.

Service fittings can cause a lot of bad readings too. Sometimes they fail to depress the schrader valve completely, this is common on 134a style fittings.

Sort out the leaks, & get the system to hold vacuum.

Was the compressor dry? some compressors ship with an oil charge installed. If so, you could have 18 ounces of oil in the system - this causes high pressures too...

[Mattman]

Sounds like a piccolo condenser. They have parallel paths, instead of a single pass. They are more efficient, but can hold less refrigerant too.

I have a 1993 F150 with dealer A/C.

Which engine is in your 150? and which compressor model is installed?

Finding the leak is the first order of business. If it won't hold vacuum it may be a bad seal - or an issue with your service fittings / hoses / manifold.

Testing the manifold & hoses is easy enough. Use a 1/4 tube union to join the high & low lines. Connect vacuum to the center port. Open the valves, pull a vacuum & close the valves. Shut the vacuum pump down, & disconnect it. The gauges should hold vacuum.

Service fittings can cause a lot of bad readings too. Sometimes they fail to depress the schrader valve completely, this is common on 134a style fittings.

Sort out the leaks, & get the system to hold vacuum.

Was the compressor dry? some compressors ship with an oil charge installed. If so, you could have 18 ounces of oil in the system - this causes high pressures too...

The engine is a 5.8, I think the compressor is a FS10 model. Thanks for the tip on testing the line set. I was wondering how I was going to do that. Compressor was shipped with 3 oz of oil in it. I added the rest to the system.

[bohica2xo]

If it is an FS10, and all of the system fittings are Springlocks - the system is factory air.

[Mattman]

If it is an FS10, and all of the system fittings are Springlocks - the system is factory air.

The only springlock fitting on the entire system is the one at the evaporator where the orifice tube is. All of the rest are threaded fittings. I tried to upload a photo of the compressor but it wouldn't work. It looks like every fs10 in every google photo though. There was no compressor on it when I bought it though just a bypass pully. I bought parts for a "factory air" system though so I'm pretty sure an fs10 is what I bought.