North American Turbocoupe Organization

quick AC question
Tedybear315 Offline
Junior Member
Hello all.

Trying to get the HVAC working on the ol' bird.  It has the R134a conversion done to it already.

I'm suspect of the orifice tube as some of the pressures I'm getting are not really making sense.

Gave it a basic charge and got 175-200 on the high side.  Now it's only about 75 out.  So I'd expect 140-170 as a rule.

Low side pressure should be around 20-25.  It's running at 10-15lbs.  I think we might have a partly blocked orifice tube.

I noted via the parts system that while its possible to obtain the tube-  It requires an install 'kit'.  And of course it's cheaper after all the expense to just replace the hose itself with the orifice tube already installed.  Thankfully once you pull the intercooler off the engine, the parts are not to hard to access.

If I need to replace that line,  I'll probably do the receiver/dryer at the same time.  One thing I do need to dump?

The pressure switch is first on the list.  The contacts are pretty bad with the crust, and after replacement of the connector it's working for now-  But after a while the switch activation goes from 8ohm to 85ohms if you wiggle the switch.  Contacts are in bad shape.  It's actually screwing with the relays.  The switch 'closes' and it's hit or miss if the compressor AND fan(s) kick on...or just the fan(s), and not the compressor.  When I would twist and/or wiggle the connector it would fix itself.  So I know that switch is on my short list.

Questions:  (As I have the tools, but the last time I did auto A/C was 30 years ago)

They make 2 pressure switches:  R12 and R134a.  The R12 uses different pressures of course (And frankly could be creating some of the issues I'm having)

Should I order and install the R134a one?  Considering someone did retro fit things years and years ago.

2nd question:  Is it needed to discharge the AC system to replace the cycling switch.  I see several photos where there is a schrader valve, and it's just a simple remove and replace and not discharge the entire system.  And other sites state to discharge the whole thing (which I will need to do when I address the orifice tube).  But for the time being,  just to replace that switch and see if things correct a bit-

Just trying to limp things along a bit.  If the new switch brings the pressures back inline a bit, then it will save some work.  If not?  We will still change out the hose and the receiver/dryer as it is from 1988...



Jeff K Offline
Most CCPS I have seen have an adjustment screw between the electrical terminals that allow you to adjust the on/off pressures. Might as well get the 134a switch assuming it has the correct female threads and the correct O ring.

No need to discharge system to replace CCPS. Fitting on the accumulator / dryer is a Schroeder valve.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
11 Crown Vic Interceptor
14 Toyota Camry (wifes car)
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized

Users browsing this thread:
1 Guest(s)

Theme © iAndrew 2018 - Software MyBB