Ok, 99 with automatic climate control.

If the a/c is on, it blow ice cold for maybe 15-20 mins and then the a/c button will start flashing and shut the a/c off.

The R134 has been sufficiently charged so it's not low.
The manual says that if the coolant or oil gets too hot it will shut the a/c off. The coolant was only at 220F so it's not that. I don't however know what the oil temp was each time it has shut off.

So, any ideas why the a/c keeps shutting down? No codes for hvac in the dic. Thanks in advance.

 

Any codes at all?

I'll bet you fan relay codes would also shut down your A/C.

 

Bad electronic controller ?

 

Did you add any refrigerant to it yourself? Too much and it will over-pressure and shut itself off. When its on, are the radiator fans running?

 

I will have to check on all of the above. I did add R134 to the system. It then worked perfectly for about a half hour and shut down again.

 

Ahh....let me explain the little that I know...which isn't much. I too added some to mine and within a short bit, had it shutting off and on for me. R134 is not the same as the old R12. For these systems, normally the refrigerant is sucked or pumped out and measured during that process. Based upon the local temperature at the time and the system amount required, a specific amount of refrigerant is pumped back in after the system has been evacuated. Too much and the overpressure sensor will trip it off.
My recommendation is to take it to a AC Shop who should only charge about $50 to do the work for you and will do it right.

 

So many things it can be. Overpressure is one. Something in the system not functioning so the system shuts down. Fans being one. Another one that can happen is a faulty hi/low pressure switch. Need to take it to an A/C tech and put it on the gauges as well as check for codes. I had a faulty low side switch that was acting up on me once. replaced and it stayed on.

 

 

Just remember that R134 pressure is difficult to read. I think you added too much. I know that my system was low, but pressure readings said it was correct. It was not until I put a vaccum on the system and then starting pumping freon back in that it registered low on freon. I believe you should put a vaccum on your system and completely recharge it. That should fix it.

 

I had same problem and found it to be the ambient temperature probe failed and it disabled the A/C unit to keep it from freezing up.

 

I am having poor cooling and want to evacuate, leak test and recharge.
In the past the low pressure switch on most systems was just that A SWITCH. Understand that the one on the C5 is a transistor. Can you just short out the two wires after letting some freon in to allow the compressor to run? Used to do it that way but is this what you should do to the electronic switch?

Understand that the poor cooling might be due to a restriced expaqnsion valve in the line. Any comments on changing this little item?

BIGHANK

 

If you are going to evacuate the system and recharge with factory specified amount it should not be neccessary to worry with jumping any switch unless it is bad. I add about a pound of liquid into high side then start a/c and add remainder of gas into low side.

The orifice tube (expansion device) is very easy to pull (one bolt 13mm wrench?) in liquid line near dipsick and can be cleaned in most cases with a blow gun and compressed air.It is also a good indicator of compressor wear (metalic particles) trapped on the screen.Remember the direction in which you remove it! If I remember correctly the longer coarse screen faces toward front of car.

 

I have replaced expansion valves, compressors and condensors and have a vacuum pump which can pull 30 inches of mercury. If I open up the expansion fitting in the line near the dipstick do I need a new O ring or gasket before reassembling the tubing?
On previous systems I found it necessary to physically jump the low pressure switch (when it was really a switch) before I could get the compressor going as simply trying to inject some freon into both the high and low side of the compressor did not give me enough pressure to allow the compressor to run. BIGHANK

 

Bighank
I have reused the o-ring without any problems however they are very cheap as is the orifice tube.Some chain auto supplies such as Pep Boys also sells a kit with both. Also wipe a smidge of refrigerant oil on the o-ring.
I understand what you are saying about jumping the pressure switch to keep the pump running. I also did this on the old R12 systems when topping off a low charge specially on a cold day when the can would not boil off quick enough. With a complete recharge and under vacuum you can get enough liquid refrigerant in to allow the pump to run fairly consistant while dumping gas to top off.I never have messed with the switch and cant help with what wires to play with.
Hope this helps and good luck with it!
Tom.

 

Possible. If it's flaky (intermittently failing) it will shut you down too. Good news is it's a cheap fix (and easy). Disconnect the battery first so after the repair the system can reset when power is applied.

 

Thanks for the info. The new Delco part for the orfice tube is just over $2 and the valve cores for the high and low pressure side are just over $4. The old cores seem to be leaking as I got pressure taking off at least one of the caps. Is there ONLY 1 O-RING used with the orfice tube or is there one at the place where the front tube meets the rear tube and another one which appears to be near the middle of the orfice tube?
The parts manual shows NOTHING but the service manual shows the orfice tube and the O-RING on it. Have never opened this particuliar type of GM system so I don't want to be caught missing a $1 O-RING.
BIGHANK

 

Only one o-ring on the line itself. It will usually stay on the spigot end of the line (toward front of car) when you pull it apart. The new tube will come with its own internal sealing o-ring.
Good find on the leaky schrader valve! Now is the time to replace them.

Kinda feels like we are stealing the original posters thread here.Have been following it to see how he made out.

 

According to the parts list there are two different schrader valves listed.
One is part # 3041827 (Delco 15-1119) which has two different names (core A/C refrig serv vlv w/o O-ring) and (valve A/C refrig press sen w/o O-ring) which looks like a regular tire valve core (long and thin). I believe this 2nd description for this part number is eroneous.
The parts manual also lists a valve A/C refrig high pressure service part # 10245819 (Delco 15-5528) which in the picture on GM parts shows it as a short and stuby tire type valve.
Since these things cost about $4 to $5 I don't want to get one I can't use. Do you know if the valves are the same or different? Can I get these out using a standard tire valve remover which has a small shaft which fits over the plunger stem and unscrews it out like a tire valve or is the depth too great to use a standard remover. If so how do i get them out? Do i need a special tool? BIGHANK

 

The part description sounds correct.The long thin core for the suction line and the stubby larger diameter for the high side.I believe the thin core may also be used in the pressure switch port with an additional o-ring between the switch and valve body.
I used a commercial a/c core tool for the suction and yes it does have a long thin tube to reach and engage the core. The high side appears to be quite larger and I have never had to replace one, so no help there. However I would be cautious using substitute tools, if you bugger those internal threads it will cost you a new line.

 

Advance Auto has the valve core tool #59302. Two sided; for large core on one end and small core on the other. $4.94 plus tax. Tried it and it will loosen them. They aren't leaking MUCH as when I cracked them just a sliver I could hear the sizzling of escaping gas and when tight no appearant leakage. But while I'm at it will replace them anyway. The cores are about $4 and change from ACDelco wholesaler and the orifice tube is just over $2. GM service manual says to remove the bolt holding the front and rear sections of the expansion line and then pull the orifice tube out with needle nose pliers. Will also try some NU BLAST condensor cleaner to get the crud off of the outside of the condensor fins. Similar to NU BRITE but doesn't need to be rinsed off. I'm going to rinse it anyway. The decal on the car says that only 1.74 # of freon is used in this system (or close to that, know its about .12 # less than 2 14 oz cans}. Since you never get all the gas out of the cans I figure they want you to add 2 cans from an evacuated system. Never saw a system that used SO LITTLE FREON. Was in the habit of using like 3 or 4 cans but that was R12. Does that sound about right to you? BIGHANK