A/C problem..blows cold then warm. Help..
 

Ok so this has got me going crazy. I have a 98 Acura EL(basically a 98 EX). I took out the old freon out and refill to proper spec twice already, and checked for leaks(none). So the problem is, when i turn the A/C on most of the time the compressesor kick on and A/C will work real good..but out of nowhere it will start blowing warm air then cold..back and forth. I've noticed when this happens, the compressor kicks off(warm air) then when it kicks on(cold air). Condenser fan is always on even when the compressor kicks off.

What should I start replacing? Some people say compressor or eletrical problem. Please help...

Re: A/C problem..blows cold then warm. Help..
 

Did you evacuate the system prior to recharging with refrigerant?

Have you checked the compressor clutch gap?

Attachment 460786

Re: A/C problem..blows cold then warm. Help..
 

could be the main relay for the clutch. thats what happened to mines.

Re: A/C problem..blows cold then warm. Help..
 

Sounds like it's cycling like it should if you overcharged it , it's trning off on the hi pressure switch, you need to understand how an a/c works if you intend to trouble shoot it yourself.
You need to evacuate (suc out all the air) before charging (with liquid) and don't forget it needs oil.
You need a set of gauges, three thermometers and know how to read them.
Take it to a shop and have it done right.

Re: A/C problem..blows cold then warm. Help..
 

Exactly what it sound like

Re: A/C problem..blows cold then warm. Help..
 

System was evacuated before the refill...twice. It is not overfilled, and I know it should turn off when it's too cold. But most of the times that i shut off, it's not blowing as cold as other times.

Where is the main relay for the clutch located?

Re: A/C problem..blows cold then warm. Help..
 

You need to monitor pressures and see where they are at time of shutoff, either pressure goes too low, maybe below 25 on the LO side, I would not think that the compressor would stay off long, this means you could use just a little more freon. If the pressure goes too high, maybe over 350 on the HI side, I would think the compressor would stay off much longer. If the pressures do not seem to go much below 30ish or over 250ish then I would say that the evap temperature sensor was turning off the compressor when it thinks the evap is too cold, actually the sensor would be out of spec.

I had an Odyssey that would turn off at 17C out of the vents every time, I have a really good thermometer and I could tell when the AC was going to turn off everytime. It didnt stay off long, similar to an undercharge of freon.

Re: A/C problem..blows cold then warm. Help..
 

AGAIN ...............
you can't just guess and we can't fix it by proxy or a crystal ball.
We can only give intelligent and sometimes experienced advice.
You need to monitor the pressures to determine why it is cycling.

Sometimes the condenser (outside radiator) gets clogged up, clean it with strong detergent and a hose.
Also the evaporator (inside the dash box under the glove compartment) also gets leaves and debris in there and clogs up the air flow.

Often forgotten is the dryer canister behind the left headlight, a bitch to change.

Pressure switch failure is uncommon and doubtful if that is your problem, but is possible.

As for checking the clutch plate gap, that's unnecessary and you can check the clutch is working by just turning the air on/off a few times with the ignition on and watch the clutch plates or listen for the click.

Also check your belts are tight enough.

Ideal pressures for a 34a system are bout 35-45 low side and 200/275 high side on a hot day at 1800rpm

Re: A/C problem..blows cold then warm. Help..
 

^^Ok, i'll check out the pressure. Thanks.

Re: A/C problem..blows cold then warm. Help..
 

Good luck with the evaporator, it's a full disassemble job including the pressure lines to get it apart.

BTW, check your pressures at 1800rpm, never idle, turn the a/c on full, with air from outside, leave the doors open, give it some work to do.

If the low side is about right but the high side is much higher than norm, look for a blockage in air flow first, then check the dryer can, replacement is best.

There's a much better way to test it, but you need several thermometers and know exactly where to place them and how to read them.

Re: A/C problem..blows cold then warm. Help..
 

Oh, just a thought, sometimes too much oil can slow down the evaporation process, most Honda civics need about 3 ounces.

Re: A/C problem..blows cold then warm. Help..
 

Not to butt heads with you Sir, I dont know so I will admit it now, but lets look in a book and see how much oil goes in the whole system, I would think that it would take just 3 oz to coat all the insides of the lines, hoses, condensor and evaperator, then you need a pool of oil in the compressor???

If I work on a system, hook up my gauges, and no oil sprays out, its low on oil and at least 1 oz goes in first. Again, only from what I have read, it takes quit a bit of extra oil to slow things down. How many times does a tech run into a system with too much oil anyways.

Re: A/C problem..blows cold then warm. Help..
 

OP, please don't listen to this advice. If the clutch gap is slightly too wide, the compressor clutch either won't engage or won't stay engaged even if the refrigerant pressure is fine. It's pretty easy to measure the clearance with a feeler gauge.

Re: A/C problem..blows cold then warm. Help..
 

Trying that today. Just noticed this..the condensor fan turns off when the compressor turns off...

Re: A/C problem..blows cold then warm. Help..
 

Based on this important new information, your troubleshooting should instead focus on the A/C thermostat and the heater control panel.

Re: A/C problem..blows cold then warm. Help..
 

To bypass the evap thermostat, locate the wire coming out of the plastic case under the dash, it may be two wires or a set of two wires molded together similar to speaker wire. Unplug the connector, does the system work, if not, short the connector on the car harness side with a paperclip, does the system work. Give each try a few minutes, when the system works and disconnecting or shorting this connector does not keep the system working for a long period of time and the system still cycles off, then the system is cycling due to the pressure switch, again you need the gauges hooked up to see what is going on to make a good diagnosis.

If the condensor fan cycles off with the compressor, then the system is working normally, except the item that we are trying to find right now, evap temp sensor or a pressure issue, LO or HI side pressure. It could be a bigger issue but these two are on the top of the short list.

Re: A/C problem..blows cold then warm. Help..
 

You do it your way, sounds fine to me, just keep a count on how much you have in there.
It's actually 3-5 oz for a small system like this,depends on if it was new and dry, it only needs a small amount to keep parts wet with vapor , and a "pool" in the compressor ? what is that ? it may have oil in it when new or reconditioned, but it won't stay there as oil for long after its been run.
If you have gauge connectors that "spray" when you hook them up, buy some new ones that work, pro ones have a valve on them to push the pin once it's been hooked up so it doesn't "spray" at all.

Re: A/C problem..blows cold then warm. Help..
 

If you review the 96-00 Civic A/C circuit diagram, which I assume is similar to the 98 Acura circuit diagram, you will see that a refrigerant pressure problem or A/C pressure switch problem would make the compressor clutch disengage but the condenser fan would still run. Therefore, the problem must be localized at the A/C thermostat or the heater control panel.

Re: A/C problem..blows cold then warm. Help..
 

Agreed Ron, the condenser fan should remain running at all times.

Duane, the evaporator bypass info is good but you are incorrect about the condenser fan.
The condenser fan should run at all times the a/c is switched on.

QUOTE:
"If the condensor fan cycles off with the compressor, then the system is working normally"

Re: A/C problem..blows cold then warm. Help..
 

OK, how many times have you heard, drain the compressor, measure the oil and refill to that amount after replacement. AC techs know this to be false, there may not be enough oil in the compressor to use that amount of oil as a guide, it needs to be researched as to how much oil to service the compressor to, some (for other types of cars) even tell you to use a dipstick to check the oil level.

I like the spray telling me there is enough oil, as I stated, no spray, add some oil. You do it your way, sounds fine to me.

Re: A/C problem..blows cold then warm. Help..
 

WTF is the problem with you, if you want to argue points go elsewhere will you.
Spraying chemicals into the air is against EPA regulations here in the USA, maybe Japan has different rules.
If you don't have useful information for the guy with the problem, BUTT OUT.

I've been repairing a/c systems for 45 years so unless you have any valid info, keep it shut will you.


I hate little whippersnappers like you think they know it all after one re-charge.

Re: A/C problem..blows cold then warm. Help..
 

I am not argueing at all Sir, I am closer to your age than most of the folks on here I would guess. I have served my country in three wars and received shrappnel to my arm, I dont think that makes me a little whippersnapper. I am willing to leave it alone.