Neon AC woes

My compresser isn't coming on in my 2000 neon. I had 1.56lbs of r134a in it
which I topped up. Put leak dye in it and some oil. I've checked all the
usual culprits and finally found it to be an electrical problem. We did
this by jumping the compressor with 12v and it clicked on right away. Ice
cold air coming out.

So, does anyone have a hint as to where to start checking first? Or better
yet, does anyone have the ability to scan in a wiring diagram for the AC
system and send it to me? I'd be forever in your debt!

Mike

 

You started with 1.56 pounds and added from there? Or you added 1.56
pounds to whatever was in there already? What does the dataplate say is
the correct fill amount? And how much is "some oil"?

That doesn't necessarily mean you have an electrical problem per se.
Remember, the system has LPCO and HPCO switches (Low Pressure and High
Pressure Cut Out) that will prevent the compressor coming on if the system
charge is too low or too high. What do your low and high side pressures
look like when you jumper the compressor?

 

Sorry, it had 1.56 lbs recovered, then I filled it to the spec if 1.875lbs.
I recovered several ounces of oil (not sure exactly how much because the
machine's oil recovery tank was bubbling) and put in 4oz. I also put in
approx 2oz of dyed oil.

I don't remember what the pressure said however the mechanic that hooked up
the machine said it was within normal range and he said (as soon as he
hooked up the machine) that the pressure was good enough for the compresser
to engage.

I can take the car back in and check the pressures on both the hi and low
side. What should that car have as optimal pressure?

Mike

 

Check the pressure switch. If pressure is too high or too low the
compressor will not run. If the switch is bad it will not run. Running
with pressure too high OR too low can cause serious damage.

 

It might be the pressure sensor, however I am not sure. It seems to be the
sensor that is right on the compressor. There is one on the 'front' and one
on the 'side'. The one on the front is the one that doesn't seem to be
doing anything. It's a black plug with several wires coming out of it. The
one on the side of the compressor is white, different connector. Does
anyone have a wiring diagram to explain what these 'sensors' do and where
they are all located?

Correct me if I am wrong but I am assuming the pressure sensor on the
aluminum block at the firewall is the pressure sensor. It seems to work as
usual. If I unplug it, the fan goes off and the engine rpms lower. The one
on the side of the compressor acts the same way. The one on the front of
the compressor does not do anything when disconnected.

When I put a light on the fuse for the AC, it does not light up. The fuse
appears to be good, I did not swap it yet. There is also a relay, I did
swap it with no difference.

If I jump the sensor on the compressor itself, the compressor engages.

It's got to be a sensor or short in a wire as the pressure in the system is
good, and there doesn't seem to be any leaks the needles on the guages stay
put and don't fluctuate at all. When I did the recovery, the system gets
purged by creating a vacum. The guages stay solid at the maximum negative
pressure. If it were leaking I should see the pressures vary while
purging. There is no dye coming out anywhere.

When the machine is hooked up the pressures are normal and steady. I did
not check to see if anything changes when the compressor is jumped
(engaged).

Thanks for your time

Mike

 

Rather than be in anyone's debt, why not simply spring for the $25 for a
years subscription for the downloadable info. from www.alldata.com.
Along with the factory schematics right out of the FSM (IOW, the real
schematics specific to your vehicle), plus full TSB's also specific to
your vehicle? Surely the FSM info., not to mention the TSB's, would be
worth that much to you over a year's time if you do your own work, as
you apparently do (and I'll quit calling you "Shirley"). (BTW, second
year renewal and/or a subscription for any additional vehicles will be
only $15 per vehicle per year.)

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

That's a pretty good idea.. I'll check into it. I'd of bought a manual
already but in my area they are hard to come by for that generation of neon.

Mike