ThreeFourFive

I have a 2002 civic si. I cannot get anyone to diagnose what is going on with my air conditioning problem. The A/C will blow freezing cold air every time I start the car, if it is not too hot outside the a/c will generally work the entire time, the problem is when the weather gets HOT the a/c stops blowing cold air after a while. I notice it tends to stop blowing cold after driving it faster like on the highway, It will then only come back on after the car has cooled down. Can anybody please help diagnose what is going on with my a/c? I even went to honda but the guys there hadn't heard of this issue before and suggested it was a coolant leak. I have a feeling it is not a coolant leak so I need some help so I dont get hosed by a mechanic trying to fix something thats probably not even that expensive to fix. Thanks guys.

ThreeFourFive

ouch. zero replies.. no guesses as to what it could be ? I know its not the compressor thats about it.

eviee1973

check your evaporatator temperature sensor resistance with an ohmeter. Should be at 30 ohms at 0 celsius, 10 ohm at 30 celsius. See chapter 21 in the Civic shop manual.

ThreeFourFive

alright and if it isnt at 30 ohms at 0 celsius and 10 ohm at 30 celsius, then what does that mean the problem is? and what if it is is at those levels?

One mechanic suggested that there is some thermostat in the compressor or something like that he wants to replace.. but first wants to try putting in more coolant. Im not a mechanic so im sorry i dont understand what you are suggesting. I just want to make a suggestion to the mechanic working on my car what I believe the problem is so they don't keep fixing things. Which is the problem im already having if this guy wants to charge the coolant and then try replacing some thermostat and then there is no guarantee that my a/c is even going to work after that.

peekeesh

^^ i guess you are referring to freon (R134a) when you say coolant. anyway, yeah check the freon and see if it's low. recharge if needed and use the freon with UV dye so if the pressure goes low again, you can get a UV light and track where the leak is at.

eviee1973

There is a thermal protector mounted on the compressor, if it reaches a certain temperature, then the ac system is switched off to protect the compressor from overheating. Resistance can be checked with an ohmeter on this as well. If you do not know anything about electrical diagnosis, it would be best to go to a qualified shop, although even then they may end up changing parts "guessing" what the problem is. Some techs are thorough, others are sloppy and careless. Invest in a Honda shop manual, so you can learn about how systems work, even if you will not be working on the car yourself.

ThreeFourFive

A couple places mentioned the Thermal Protector. I am just wondering if it is common to replace the thermal protector because the thermal protector is faulty or is it a bad compressor causing the thermal protector to activate and cause it to turn off the compressor?

eviee1973

Your AC system usually shuts down due to freeze up in the evaportator (sensed by the evaportator temperature sensor), or overheating in the compressor (thermal protector senses this). Unless you have lost refigerant oil, the compressor should be ok and not unecesarily causing overheating conditions. One of those two sensor shut off the AC after a period of use when there is one of those problems detected (or sensor gives a faulty reading, fooling your AC system in to shutting down. You do not mention where you live/type of climate.

JuNiOr Ts

I had same exact problem..no leaks (checked by Pepboys)
AC work good when outside temp below 80F...
Compressor stop working when outside temp above 80F..
btw i live in socal... so at around noon to 4pm my AC will not blow cold air...
Changed my Compressor.. Now my AC is cold as ICE ALL day for more than a year now no problems

gangulyarchan

I have a similar problem in my 03 Civic EX. My A/C works when I start my car in the morning but only when I am parked and the car is in neutral for as long as you keep the car running. When I start driving and shifting gears after about 3 minutes the compressor stops kicking in and I get warm air. Then when I stop the car and restart the car immediately the compressor will not turn on even when the car is in a standstill. After a couple of hours again it goes back to the situation I mentioned above once the car cools down.
I got a recharge done, no leaks, both fans run, got the thermal protector sensor replaced today thinking that might work. Again runs while in neutral. When I drove for 5 mins in 2nd gear but then I get to the road and drive normally and then again about 2-3 mins later stops blowing cold air and have to wait for engine to cool down.

I am back to square one . Any suggestions are welcome
Please Help!!

ThreeFourFive

Fixed it. Not exactly sure what they did. They rewired it so it would bypass the sensors that would shut off the compressor somehow. Ended up being a cheap fix. Annoying as hell though and it took them forever to figure out as they kept guessing what could be wrong with it and not charging me for the work they were doing until they figured out the right cause of the problem.

92b16si

I have the same problem. my compresses stops and goes when ever it feels like it. it smells like burning belt every now and then, Iam stumped.

ThreeFourFive

mine isnt exactly 100% working again now either.. though it works more often than it was before. Is it possible the the compressor needs to be replaced? Or does the compressor either work or doesnt work? This problem is really awful in the heat. Has anybody fixed their intermittent a/c ? Seems like its a more common problem than i originally thought.

gangulyarchan

@ ThreeFourFive- This post has been inactive for a long time and maybe you might have fixed the issue but I will just update with what my mechanic did to fix the issue. He realized that the A/C clutch would not engage once the car heats up, so he took the clutch out and removed two out of three metal shims from between the compressor and the clutch (known as reshimming). A/C has worked perfectly since even in extremely hot weather. The other solution would be to replace the compressor with a new one but the reshimming is much cheaper. Hope this helps.

slcfireguy

I agree with eviee1973 it's the thermal protector on the compressor. It has two wires and one screw. I replaced mine last year and it fixed the problem immediately. Only problem is one year later and the problem came back. I don't think they build the sensors very well. I'm thinking about bypassing it but i'm afraid of burning up the compressor. Funny thing is other compressors don't even have these sensors.

One side note, if the ac blows perfectly cold air then just shuts off like flipping a switch it's not low on freon (coolant).