Mechanic Bypassed ECU and placed a Thermostat instead :( ... HELP!

**darthvord** · January 10th, 2012 02:16 PM

My car is an 06' Chevy Optra 1.6 LS Wagon (Automatic). Last year na notice ko na nawawalan ng lamig yung kotse at humihina yung hangin. So I thought that it might be because it's dirty already. SO, I took it to the shop and the mechanic said that my compressor clutch is not disengaging and that's why its ice-ing up. He said that everything was OK, no leaks and the system is is clean except for clutch problem. The mechanic said that it might be the ECU acting up, he suggested that we add a thermostat and bypass the ECU.

Not being a car nut (and fearing that I'd be buying a new ECU... which will cost me most of my limbs) I asked him to go ahead with the procedure. It worked, the compressor disengages automatically and it doesn't ice up anymore. Problem solved!

Or I thought it was. After a few months, I am now noticing quite a significant power loss everytime the compressor kicks in and a faint "gurgle" when the car is in idle and below 1K rpm. And also sometimes the compressor won't turn on (turing the AC switch on and off after a few minutes solves this issue... pretty annoying)

I've read somewhere that my car automatically cuts off the compressor if it detects that its under load (climbing a hill, overtaking, etc.) and knowing that we've just bypassed the ECU, I might be placing too much stress on my engine because of this. I now want to take it to another AC shop and remove the thermostat, and have it wired the way it was before.

My question now is What could be the cause of the compressor not disengaging? What should I look for and what should I tell the mechanic?

Thanks a lot in advance, and sorry for the eyestrain.

**shadow** · January 10th, 2012 03:05 PM

your electronic thermostat is busted, ang ginawa ng mechanic eh pinalitan ng manual thermostat...

**darthvord** · January 10th, 2012 04:55 PM

Originally Posted by shadow

your electronic thermostat is busted, ang ginawa ng mechanic eh pinalitan ng manual thermostat...

So, walang sira or hindi sya related sa ECU ko and will it solve the engine problem? And magkano kaya yung electronic thermostat? Ayoko ma loko ulit, hindi kasi ako ganung ka runong with regards to technical stuff sa mga kotse. Thanks sir for the prompt reply.

**yapoy86** · January 10th, 2012 05:06 PM

for me, manual thermostat is better than the electronic sensor. electronic thermostat is just a thermal resistor that varies the resistance relative to temperature.. most of these sensor maintains a -5degree temperature (cooling coil temp) that is why your compressor works longer to achieve the -5 degree temp. this will be the cause of ice formation on your cooling coil. your sudden low engine power might be the compressor engaging while driving unlike before that your compressor is always engaged..

**fourtheboys96** · January 10th, 2012 05:14 PM

just turn off the aircon during steep climbs. it won't take too much effort doing that.

**darthvord** · January 10th, 2012 05:22 PM

Originally Posted by yapoy86

for me, manual thermostat is better than the electronic sensor. electronic thermostat is just a thermal resistor that varies the resistance relative to temperature.. most of these sensor maintains a -5degree temperature (cooling coil temp) that is why your compressor works longer to achieve the -5 degree temp. this will be the cause of ice formation on your cooling coil. your sudden low engine power might be the compressor engaging while driving unlike before that your compressor is always engaged..

So sir, this is normal and is better than buying and putting an electronic thermostat back on? I've had cars before that have manual thermostats but it never takes that much power away from the engine and will it have any direct effect on the engine? The car BTW is only at 65K on the odo (home - office daily driver) Thanks!

**yapoy86** · January 10th, 2012 05:22 PM

yung suzuki wagonR ko with k10a engine pag medyo na sense nung ECU na hirap yung makina tapos nag press ka pa ng pedal automatic nag disengage yung compressor even though na nag convert na ako sa manual thermostat....

bottomline your car's ecu still have the control over your compressor and not your thermostat

**darthvord** · January 10th, 2012 05:32 PM

Originally Posted by fourtheboys96

just turn off the aircon during steep climbs. it won't take too much effort doing that.

That's what I'm actually doing.

But problem is, when I turn it off it sometimes doesn't turn back on. The cabin gets warm pretty quick and I have to roll the windows down... and that's not really safe especially when you're driving at night and on a dark shady place with your family.

**Ry_Tower** · January 10th, 2012 05:38 PM

Originally Posted by darthvord

That's what I'm actually doing.

But problem is, when I turn it off it sometimes doesn't turn back on. The cabin gets warm pretty quick and I have to roll the windows down... and that's not really safe especially when you're driving at night and on a dark shady place with your family.

Parang may problem na sa aircon system mo sir. Baka busted na ang expansion valve mo.

**darthvord** · January 10th, 2012 05:44 PM

Originally Posted by yapoy86

yung suzuki wagonR ko with k10a engine pag medyo na sense nung ECU na hirap yung makina tapos nag press ka pa ng pedal automatic nag disengage yung compressor even though na nag convert na ako sa manual thermostat....

bottomline your car's ecu still have the control over your compressor and not your thermostat

Hi thanks sir, I'll try this out. I usually just hit the thermostat switch kapag hirap. The engine rarely goes above 3K even when climbing even with the AC on, and I'm really not heavy footed on the gas.