Help with a/c PLEASE

[jhrusk]

I have a question concerning a/c pressure on a 1985 gmc.This is what I have done.new compressor,new dryer,new orifice tube,new o-rings.I flushed evaporator and condenser and installed adapter fittings for 134a.I vacuumed system for an hour and had everything working well.I noticed the next day it was cycling a lot so I looked into it and found the old high side schrader valve was leaking.I got it replaced and vacuumed and re-charged system.It is a fair amount cooler today maybe 55-60 degrees outside and it seems to cycle more frequently, on the low side compressor cuts off@ 27psi and cuts on @ 49psi.High side cuts off @ 125psi and cuts on at 75 psi.I am no a/c expert by any means so I really dont know if I am in the ballpark,and as cool as it is today you normally would not run a/c anyway.Any thoughts or suggestions on this.Thanks in advance.

[old Rusty C10]

anyone?

[hatzie]

You may bleed away your R134a refrigerant over the winter months without barrier hoses.
I assume you used a Variable Orifice Valve. Everything I've read says R134 has better cooling performance with a VOV.
I also assume you dumped the compressor oil out and used Ester oil since you completely flushed the system.

Here's some retrofit information from BMW E38.org
More here.
----------------- quote ------------------------
HIGH PRESSURE CUTOUT (HPCO) SWITCH
I think a high pressure cut out switch is a worth while safeguard. A HPCO switch could save a retrofit from being a monster! I have heard of retrofits of dual evaporator systems that ran such high head pressures that the hoses swelled and started leaking. Red Dot manufactures a switch called a Trinary switch PN 71R7550 that is reasonable in price (about $20.00), performs functions needed in a retrofit and R134a compatible.
Four Seasons part numbers are: 35899 (male style), 35901 (Female 1/4" service port style), or 35922 (universal male or female style).
It performs three functions:
1- It's a high side low pressure (HSLP) switch which opens at about 23 PSI. It would keep the compressor from coming on if the refrigerant is lost or ambient temperature is low.
2- It's a HPCO switch that opens at about 325 PSI. It would stop the compressor from operating if the head pressure goes above 325 PSI.
3- It's a cooling fan switch witch closes at about 220 PSI. It could be used to control a cooling fan. Its part number is: RD 71R7550, 4S 35922, EV A8025, MUR 207094, TA 11-2629
------------------- end quote ------------------

[jhrusk]

hatzie, I do not know if it is a vov,also the compressor came sealed with 7 oz. of pag 150 I think it was.

[cjracing15]

I would recheck it on a warmer day. like 70 -75 before i really worried about much. The ac will cycle more on cooler days.

[88Jimmy4x4]

Originally Posted by cjracing15

I would recheck it on a warmer day. like 70 -75 before i really worried about much. The ac will cycle more on cooler days.

x2

[jhrusk]

Thanks guys for the replies.