K heres what I know about my AC. Pump doesnt com on when I push the button. It had 0 psi when I took it in. put 19 oz. in like the label under the hood says. When we made the pump turn on bypassing the dash switch it kicked on and built up way to much preasure. running preasure is somewhere around 200 and it ran up to 300 before we stoped it and the vacume should have been around 20 and it was sukin around 80. So my guy tells me that theres something plugging the system but he doesnt know the Civic very well and would need a AC wireing diagram and to tear the car apart. said somewhere between 500 - 1000 bucks depending on how fast it got fixed.

So my question is does anyone know a common problem with these or do I just have to tear the whole thing apart part by part hoping to find something plugging something.

Thanks.

 

First of all, it's a compressor (not a pump). ;-)

The system is pressurized when operational, but vacuum is used to check for leaks. The refrigerant coming out of the compressor is the high-side pressure (the beige or red cap usually with an 'H' on it). And the returning refrigerant (coming from the condensor - that radiator lookin' thingee up front - is the low-side... blue cap).

I just had a similar issue with my '95 HB - too much high-side pressure (over 400 psi!!!), and proportional low-side (80-100 psi). After replacing the expansion valve (in the evaporator core, behind the glove box), I'm getting much better numbers (190-210 high-side, and 30-40 low-side) and the compressor's circulation is where it's supposed to be.

That's WAY too much for this kinda job - the part is less than $30 at AutoZone. Unless you're OK with dropping that much coin with some guy that is going to charge you based on how long it takes him to fix it. Sorry, but that's why reputable mechanics can give you an estimate up front - they know how much to charge for various jobs based on experience. I'd find another guy.

Or do it yourself. Have an A/C tech evacuate the system, replace the expansion valve, and take it back to the A/C tech to have him leak-test and recharge the system. Go from there.

 

If you jump power direct to the compressor so it runs but the condenser fan doesn't come on, you will get excessive pressure like you had. You really need everything working. It's not complicated if you have a diagram. When you press the button, does the condenser fan come on? Also the engine should speed up. If it does that, check the compressor relay which is mounted near the condenser.

Now that there is pressure in the system (unless it has already leaked out again, which it will do), check the pressure switch on the condenser is closed. The other controls are a temperature control on the evaporator, the dashboard button, the fan switch (must be on 1-4, compressor will not run with interior fan off) and of course the fuses.

 

Or you could just do the easy and cheap stuff that mk378 suggests first.

 

well I went out this morning and the AC worked fine. turned on and off great. but when I went home from work it wouldnt come on. Im wondering if theres a over heat temp sensor that would make the thing not come on.

Anyone know a good place online to find wiring schematics?

 

Exact same thing is happening to me, but i know it's my A/C clutch that is faulty

 

Mine's kinda the same way - absolutely awesome cold air in the morning... not so much as the day gets hotter. Keep in mind that the condenser on our cars are about as small as they come, meaning that the hotter it gets, the less efficient it will be at cooling the refrigerant.

What I did discover is that my compressor would bog down seriously when there was the recommened amount of refrigerant in the system (19 ounces). This would also cause the compressor to get hot - which would make sense if there's a protective feature to keep the compressor from overheating and giving up. I'm also not ruling out the fact that my compressor may be the whole 190k miles old. However, it seemed about as good as it could get with just 1 lb of refrigerant in the system. I have a theory that there's too much oil in mine, and need to pull down the system and clean out the lines before recharging to see what's up. I purged a little of the refrigerant out of the system a few times and the air temps kept getting cooler. However, I think I pushed past the 'sweet spot' and bled too much out because now it's blowing warm air again. Oh well - I have access to an A/C machine and my pal's a certified A/C tech, so I can keep posting what I find out each time I mess with it in hopes that it might help someone with their problems.

Speaking of - I'll be clearing the lines and recharging again this weekend, so I'll be back with more information.