Corolla GLI Aircon Problem

[xfreemanx]

My Corolla is a 1996 Toyota Corolla Gli, 1.6L, Manual Transmission, EFI.

I have been having problems with my A/C system. There appears to be no pattern on when this is occuring. Whether it's a cold or hot day, fan in the highest or lowest setting, temperature control in max or min setting etc., the A/C just erratically quits working. I've noticed that sometimes, the compressor clutch engages and sometimes, it doesn't. So I did the following to trace the possible cause of the issue:
-There is enough refrigerant. Minimal bubbles on filter drier sight glass.
-Clutch is functional. If I directly energize it or short the relay contacts, the clutch would engage and AC works.
- Compressor Relay has been replaced (just in case). No AC related blown fuses found.
- Checked the voltage across the relays. Whenever the issue happens, no 12V DC is being read.
- Disconnecting or shorting the pressure sensor does not help in engaging the compressor.
- Checked if the temperature setting (variable resistor) is functional. I got good readings from min to max setting.

What happens is, when I turn on the A/C, only the blower turns on. I also noticed that erratically, the engine's idling would go up but the compressor isn't simultaneously engaging. If I disconnect the A/C "blackbox" (under the dashboard), idling would get back to normal.

I am now suspecting that probably something is wrong with the "black box" that serves as the A/C controller. No observable burnt components there so I just cleaned the connectors with a contact cleaner. Until now, I am still getting the erratic A/C performance. What could be going on? How can I know if the black box is kaput? How about the thermostat? Could it be the culprit? What other sensors play a part in turning the compressor on? How do I proceed and troubleshoot?

Salamat sa mga makakatulong. Pinost ko na rin sa http://www.allexperts.com yan. Di pa nakakasagot yung mga Kano. Pinoy diskarte pa din inaasahan ko.

[Mojo]

magnetic clutch ng compressor?

used to have the problem, bumitaw, engage ang magnetic clutch kaya up and down idling din

[xfreemanx]

Thanks for the quick reply Mojo.
Pero tingin ko hindi clutch e. Nag rekta na ako ng switch sa relay papunta sa magnetic clutch. Tuloy tuloy kapit ng clutch at lumalamig ang aircon. Kaso, walang idle up na nangyayari kaya bumababa yung RPM hanggang 700, minsan nga namamatayan pa ako ng makina.

Saan ba magaling na A/C shop na reliable at mapagkakatiwalaan? Ano kaya problema ng AC ko?

Tnx

[orly_andico]

better visit Mang Mario (search for directions here). He's VERY well recommended, I've also tried his service myself.

i would think there's something wrong with the thing which controls your A/C relay. Kasi you say the idle doesn't go up when the A/C engages? the idle-up is implemented by the idle air control valve (since GLI car mo, it uses an ECU/computer box).

i think the "black box" inside your dash IS THE ECU, not just for the A/C. mga 6000 din yun surplus but it's main job is to control the engine and if your engine is running, it's doubtful na may sira yun...

[xfreemanx]

Galing na din ako dun. Recommendation nya, convert na lang daw to conventional na thermostat controlled. Bale may ikakabit sya na standalone thermostat at yun yung mago-on off ng compressor. Gagana yun kung sa gagana, kaso di yun yung best solution kasi wala nang idle-up compensation na mangyayari. Bypassed na din yung temp control setting sa dashboard plus yung iba pang sensors (like hi press) na binabasa din ng AC box.

So you lose performance and protection. Naku, sakit sa ulo to. May iba pa bang shops na recommended kayo? San ba makakabili ng surplus na AC controller. Ala sa banawe e.

[zeagle]

Looks like an electrical problem dude. What aircon do you have? Is it a Denso? If it is, I have an electrical diagram. We can trace it from there. I don't recommend altering your electrical system. Like what you said, it is not the best solution. Worse, it's gonna give headaches to next person whose gonna fix your car.

[xfreemanx]

Zeagle,

Yes, I think it is a denso. can you forward me the diagram please? fr33m5n*yahoo.com
Thanks!

[zeagle]

Zeagle,

Yes, I think it is a denso. can you forward me the diagram please? fr33m5n*yahoo.com
Thanks!

Sorry dude I don't have a scanner. Daan ka na lang sa office.

[non-vtec]

di ba sanden ang oem a/c ng gli?

[revoGSX]

try to open the black box of the aircon, baka meron lang busted relay sa loob nyan hehe..

yung liteace namin eh relay lang sira sa loob ng black box, pagka-replace ng relay eh back to normal na ulit ang aircon... pero the black box of the corolla might be different hehe..