No Idle up when A/C is turned On

[nonanajo]

Hello. After a hard winter in NY the sun has finally started to show its colors. But when i turned my A/C on my 1993 Toyota Camry it will not turn on. Heater, Fan, Rear Window Heater works without any problem. I disconnected the A/C amplifier and checked the connector with the below results and in these conditions, Ign = ON, Temp = MAX Cool, Blower = HI:

5-Ground= Continuity
9-13 = 1.5 Kohms
14-13 = 120 Ohms
12 - Ground = 12V (A/C On or Off)
2 - Ground = 0v
10 - Ground = 12V (A/C On or Off)
8 - Ground = 12V (A/C On) , 0V (A/C Off)

I checked the A/C switch and relays and all appear to be good. Can the Low pressure cause it not to IDLE up when A/C is turned on? What can i be missing? Please help. Thanks.

[Stillrunning]

Originally Posted by nonanajo

But when i turned my A/C on my 1993 Toyota Camry it will not turn on.

You mean the engine will not start?

Can the Low pressure cause it not to IDLE up when A/C is turned on?

Or do mean your idle-up just does not work?

On my system there is a separate idle-up valve which is an electrically operated VSV. I suspect the A/C amplifier controls this from a signal from the A/C clutch circuit. Location looks to be PS behind intake manifold.

[nonanajo]

Originally Posted by Stillrunning

You mean the engine will not start?

Everything Works good on the vehicle. It is the A/C that will not start.

Or do mean your idle-up just does not work?

The Idle will not start.

On my system there is a separate idle-up valve which is an electrically operated VSV. I suspect the A/C amplifier controls this from a signal from the A/C clutch circuit. Location looks to be PS behind intake manifold.

I see that some of the voltages on the A/C Amplifier plug are not within specs. Thank you very much for your time.

[nonanajo]

Update: Sight glass shows no indication of R-12. To recharge I believe i need to jump start the compressor since he does not kick in, right? If so, how do you jump start it? Can the low pressure cause it not to idle up? Thank you all for your time.

[Stillrunning]

If no R12 then you'll have to fix the leak first. If A/C clutch is not engaging due to low pressure there's no reason for idle-up, the compressor would have to engage first. You'll need to source R12 gauges/connectors and refrigerant, it will be expensive if you can find it so more reason to fix the leak. If full charge there will be no indication in sight glass, best to test pressure first. If there has been a leak for as long as you indicate then there may be moisture in the system which you'll have to vacuum out. New filter/dryer is usually advisable. Possible faulty pressure switch can be test jumped to allow system to engage.

[Mister_Perkins]

Your compressor had an rpm switch on it As well. If it's not working properly, no ac

[nonanajo]

Thanks to all for your time. How can i jump the pressure switch? Once jumped, if the A/C works does this mean I need to replace the pressure switch? Also, how can i test the RPM switch? Thanks once again.

[Stillrunning]

Originally Posted by nonanajo

How can i jump the pressure switch?

I believe it is just a two pin plug, switch closed with pressure. Disconnect the plug and short the two connector contacts on the harness. It does not take much pressure to close the switch so if shorting the switch let's the compressor engage then you will have little R12 in system (leak) or the switch is defective. If you get normal cold air then switch is defective, if no cold air then R12 has leaked down and you'll probably need to use a substitute refrigerant.

Also, how can i test the RPM switch?

If the rpm sensor was detecting slower rpm then the light on A/C switch would blink. Usually it means a loose belt.

[csharp100]

Like Stillrunning said, if there is no R-12 refridgerant in the site glass than you need to fix that leak. Do NOT use the "leak-stop" for ac systems. All that stuff does is gunk up the system. Believe you me, I did that and ended up taking my truck in for ac service. Unless it is relatively simple, I would take it in for service. To me it was worth the money and I did not have to stand out in the friggen hot sun tracking down an ac leak. If you cannot find R12, convert it over to R134a. Plus most good shops come with a warranty.

[nonanajo]

Thanks for all the help. A/C is back up. It was empty. Maybe the winter? This is what i did:
1) Jump the compressor like STILLRUNNING recommended and felt no heat.
2) prior to reading CSHARP's recommendation i bought a R-12 substitute from EBAY.
3) Immediately after emptying one can of freeze-12 into the system the A/c began to get cold. Emptied oil and stop leak then poured one more can.

A/C is colder now than my Toyota Sienna. Thank for all. Got tired of sweating on the commute. Take care.