Hello,
I am having trouble out of my civic. The A/C does not work (blows hot air only). I do all of my own mechanic work but when it comes to A/C I Might as well be working on the space shuttle lol. I bought this car from a family member knowing the a/c didnt work. She told me, she had it converted to 134a and when she did she spent $700-$900 doing so, Im not for sure what parts they replaced or any of the details but she says the cars a/c system never really worked all that well and she was the original owner. I was wondering if someone could help me out here is what its doing.

Car Specs: 1993 Civic Ex Coupe 1.6l

Problem: Turn A/C on while at idle (500-800 rpm) the compressor cycles every 5-6 seconds when it does cycle the engine dives down to 250 rpm and almost stalls then the compressor kicks off and the engine idles back up. Very rarely at idle the system will blow cold but i have had the car for 6 months and its only blown cold 3 times.

Turn on the A/C while maintaining speed or accelerating (25%-50% Throttle) the car surges im assuming the compressor is cycling and causing this but at this rpm range (1500-3000 Rpm) it only cycles for 2 seconds then has a 3-4 second pause before cycling again (and never blows cold air) it drags the engine down by at least 20% in power. however i do realize this is a tiny 4cyl and a/c is gonna take power away but im pretty sure it shouldnt be surging this often .

What I have done: I have removed all of the 134a and replaced it with the proper amount ( did nothing ) I have checked all connections to the compressor. and i have sweat more than i can ever remember lol.

I do have a/c gauges for the high and low pressure sides but im not for sure what the specs are for this car with 134a in it. and i do not remember what the readings were the last time i checked it if you need the pressure readings let me know and i will post them ASAP

Thank you for reading. And thank you for your help
Chris Elrod

 

I can tell you right away that it is building too much high side pressure-- main reasons are:
condenser fan not working (should be on all the time the compressor is engaged)
overcharged with refrigerant and/or oil (since this is a conversion, the old mineral oil should have been removed and replaced with ester or PAG)
refrigerant contaminated with air

 

so what would you suggest i do. should i reclaim some of the refrigerant and see what happens? also do you know what the spec pressure amount should be when running 134a in this system

thanks for your reply

 

some one also told me it could be an expansion valve problem ????????????? what do yall think

 

Does the condenser fan work?

 

yes it works

 

It seems that you have air in the system or too much refrigerant. After recovering the old refrigerant, did you deep vacuum the A/C system for a couple of hours prior to adding 21-23 oz of R134a?

 

If you're sure it's the proper charge and no air, get some pressure readings next. But I think you're looking at taking everything apart to flush out the excess oil. Since it hasn't worked properly for years I suspect that someone put too much oil in during a previous service.

Also I'm curious if it has the same condenser as the factory 134a models from 94 and 95, or is it different? Especially if the same, you should be using about 18-20 oz of 134a since that's what the 94 and 95 needed.

 

I did pull vacuum on the system but only for about 30 min. My pump would not pull past 15in for some reason. To be honest i have no clue exactly how many oz we put in it my scales batteries were dead lol. However i did have a mechanic friend who was with me and he guessed at it by checking the psi on the gauges ( I dont know how,why, or if you can even do that accuatly) and not knowing much about a/c i just went with what he said.

When i got off work today i checked the pressures car running a/c on full blast and they were as follows:
@ idle - High side - 375-400psi fluctuating as the compressor cycled
@ 2000-2500 RPM - High side - 450psi while compressor was engaged

@ idle - Low side - 80-90 psi as the compressor cycled
@ 2000-2500 RPM - Low side - 70-75psi compressor engaged

So I decided to take a little refrigerant out i reduced the pressures to:

Idle - Low side - 55psi compressor Engaged
Idle - High side - 225psi engaged
I did notice as i reved the car up the high side got higher and the low side got lower but they didnt seem to move in sequence the high side went up way quicker than the low side dropped.

This stopped the super short cycles now it actually cycles normaly at both idle and 50mph in 5th gear and now its blowing cold but its only about 10-15 deg cooler than outside @ idle and maybe 20 deg cooler going down the road. I know that 30 deg cooler than outside temp is all you can really expect from a car a/c unit. Now im curious how do my numbers stack up to what should be expected from a 93 civic?

Thank you both so much for you help i look forward to your input.
chris

 

I did notice an excess of oil as we relived the pressure. and how can i tell if its the same condenser as the 94-95 models

thanks