Diagnosing A/C Problems ....

SeventyMach1 · Jun 28, 2007

Yet another topic I am a noob at. I saw a guide posted a little while back ... anyone have this link?

Anyway, I remember that if the compressor does not kick on (which mine doesn't), to try to jump the switch on the passenger side canister on the firewall. I did this and the compressor DID kick on. I suppose this indicates that the switch is bad?

The Green GT · Jun 28, 2007

Switch is bad, or pressure it too low or high.

go-stang5.0 · Jun 28, 2007

Your refrigerant is prolly fine. I doubt the pressure is too high in the system, extremely unlikely. And if the compressor is kicking on then its not too low for sure. That is the high press cycling switch. It turns the compressor off when the press. reaches a certain level so you dont blow anything up. THen when the refrigerant circulates and the pressure drops it closes the circut and the compressor kicks on again and the cycle repeats. But yea just replace the switch and you will be good to go. Unplug the harness, unscrew it, screw on the new one and plug it in. Or if the refrigerant is low and the

bimmertech · Jun 28, 2007

you really need to hook up a gauge to the low side and see what happens when the compressor finally comes on(via jumping the switch)

HISSIN50 · Jun 28, 2007

bimmertech said:
you really need to hook up a gauge to the low side and see what happens when the compressor finally comes on(via jumping the switch)

The only change I'd make is to use manifold gauges if you can find some Justin.

Otherwise, just do as Ben suggested (his suggestion is generally much more feasible, hence why he made it).

If you're actually low on refrigerant, dont let it run too long with the LPCS jumpered (read: if the low side pulls down to 15 PSIG or less, I'd shut it off).

If you use manifold gauges, post up low and high side pressures and ambient temps if you feel like it.

Good luck.

SeventyMach1 · Jun 28, 2007

I will see if I can get a manifold gauge tomorrow when I go to get a new switch.

Also ... where can you buy the High Pressure Valve (front, passenger side one)? Mine was fine, until today. Started leaking when I messed with it.

SeventyMach1 · Jun 29, 2007

Anyone know the part # for that switch? Also need one for the High Pressure Valve that I broke. I have been searching EVERYWHERE!!!

wytstang · Jun 29, 2007

I just finished paying $850 to have a new compressor, accumulator, and liquid line (orfice tube) installed. It sucked but with no time to work on the car I said screw it, it's way to hot to be with out. Good luck........

The Green GT · Jun 29, 2007

Usually some A/C parts are dealer only. When i did my A/C on my Isuzu truck I had got the compressor from the parts store, and I think everything else was from the dealer. So you might have to call the dealer for these parts. But I am pretty sure you could find them in a junkyard.

SeventyMach1 · Jun 29, 2007

Okay, I found the switches. Places call them different things. Pressure cycling switch, clutch cycling switch, A/C switch interruptor, and adjustable cycling switch are a few of them.

Got one at AZ ... part #36494. Same part # works at O'reilly's.

Never did find a valve. The line "kit" was $150, so I wasn't about to go that route. I purchased a valve repair kit. Hopefully this will work.

Thanks guys.

SeventyMach1 · Jun 29, 2007

OMG!!! This thing is pissing me off. I REALLY need that high pressure valve.

That valve kit that I got came with the correct valve caps ... but the valves themselves were TIRE VALVES! Thank you CHINA!

Anyway, I thought the valve was not leaking anymore for some reason. So I proceeded. I had the system all charged with the new switch in place. I actually had COLD air for the 1st time in this car. So nice. But when I removed the manifold gauges, it all escaped. 2 more cans down the drain.

Once I get this valve, I am good to go! Any of you that have removed your A/C that are willing to part with it?

The Green GT · Jun 29, 2007

Wait I think I misunderstood you. The valves ARE just some regular tire valve cores right?

SeventyMach1 · Jun 29, 2007

See ... I guess they MAY supposed to be the same as a tire valve .... I am not sure.

I purchased yet another valve kit ... at Wal Mart this time. It is a R12 to 134a conversion kit. I only got it cuz one of the valves in there looked like the one I need for my high pressure side. Anyone know if this is the same valve before I rip open this $10 package? This kit also has tire looking inner valves. So I am not sure if I even had the correct ones to begin with. I just know my old high pressure valve innards look similar to a tire valve ... but are not quite the same.

Anyone?

HISSIN50 · Jun 29, 2007

The R134 service valves (where your manifold gauges hook up) should have been bigger than a true tire's schrader valve (the old R12 valves were closer to being the same size as tire valves, but those do not apply here in any way or shape). Our ports have a rubber ball in 'em.

And when you disconnect the high pressure switch, I believe you will find a small schrader-type valve in there - it's so you can replace the switch without losing refrigerant (a nice idea). This valve is not visible with the HPS installed on the car. This is something to really nail down absolutely because otherwise the system would evacuate (I'd crap my pants if there was NOT a schrader valve in there and the system could dump a large volume of refrigerant in your face). Do treat it like it will shoot you in the face (some will come out, even with a schrader, and this stuff can freeze your skin, eyeball, etc. Seriously).

SeventyMach1 · Jun 29, 2007

When you say HPS ... u mean the switch down close to the headlight, right? If so, I never had to mess with that one. I had to replace the cycling switch on the firewall.

That is what happened to me, though. The rubber ball in the service port (high side) did a flip and flew out. I know the service port screws out (off of the high side line). I just need a replacement port (cuz I lost the ball inside it). I can't see a way for the schrader to remove from the service port itself. And even if I did, I don't have a replacement for that either. The little one's I have are apparently for R12.

HISSIN50 · Jun 30, 2007

Justin, I think I gotcha now. For some reason I thought you had a leaky High pressure switch.

If you need new R134 service ports, that's doable for 40 bucks or less (I have part numbers saved - courtesy of our friend Al [Methodical]).

The LPCS is also an easy swap. I dont have a part number for it but it's much more common than the HPS.

kruegs74 · Jun 30, 2007

so much going on in this thread i dont know what to think. from your first post though you said you jumped the switch on the canister which would be your accumulator/dryer. that would be the low pressure switch. all that does is make sure you have pressure in the system for the compressor to run, other wise the compressor would be running dry which is bad. so most likely your freon just leaked out and the switch was not bad. now as for your current problem it sounds like your screwed, you shouldnt have any thing to do with r12 parts. any car 94 and up should be 134a. if that ball came out on the high side port you either have to look for a 134 high to 134 high side port connector (which ive never seen before but you never know), or your looking at a whole new line. after thats all said and done you might want to find out where it leaked out in the first place, maybe it was that high side port leaking the whole time.

SeventyMach1 · Jun 30, 2007

HISSIN50 said:
If you need new R12 service ports, that's doable for 40 bucks or less (I have part numbers saved - courtesy of our friend Al [Methodical]).

I definitely need part #'s! Not R12, though. 134a.

SeventyMach1 · Jun 30, 2007

kruegs74 said:
so much going on in this thread i dont know what to think. from your first post though you said you jumped the switch on the canister which would be your accumulator/dryer. that would be the low pressure switch. all that does is make sure you have pressure in the system for the compressor to run, other wise the compressor would be running dry which is bad. so most likely your freon just leaked out and the switch was not bad. now as for your current problem it sounds like your screwed, you shouldnt have any thing to do with r12 parts. any car 94 and up should be 134a. if that ball came out on the high side port you either have to look for a 134 high to 134 high side port connector (which ive never seen before but you never know), or your looking at a whole new line. after thats all said and done you might want to find out where it leaked out in the first place, maybe it was that high side port leaking the whole time.

Wow. Let me go through this again. I'll explain the best I can.

I NEVER had a leak. Compressor didn't work. It had pressure, but it was low. I recharged the system properly. My compressor still did not kick on ... ever. So I jumped the switch (that has a million names by now). The compressor kicked on. This told me that the switch was bad. I replaced the switch.

In that whole process (tinkering with the high side) ... I lost the ball inside the high side service port. So now, ALL IS FIXED ... except that port. It will no longer hold a charge becasue of that port. As far as the R12 stuff ... I bought the CONVERSION kit because it has a service port included with it that looks VERY similar to my 134a high side port. I will test it to see tomorrow I guess.

If that does not work ... hopefully JT will have me a part #, lol.

BTW, I knew our cars were 134a ... and the service port can be replaced without having to replace the whole high pressure line.

kruegs74 · Jun 30, 2007

ok got you I just got onto the ford website and got this "NOTE: The A/C service port fittings are the two-piece design. The top portion of the fitting is aluminum and is threaded to the bottom part and sealed with an O-ring seal. The valve seal is an integral part of the aluminum fitting piece which must be replaced if the seal leaks." Im sorry I didnt relise the port was a two piece design, most cars are all one piece. thats awsome for you. by the way im a mechanic at a ford dealership so im searching right now to get you a part number of thier site which isnt avalible to the public. also its true the switch could have been bad but even with some pressure in the system it still wont cycle. it will open when the system goes below 22-28 psi, it will then close the switch when pressures get back up to 40-47 psi. ill keep you posted if i can find a p/n.

Diagnosing A/C Problems ....

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