kwiktsi

My 94 is having AC issues. The compressor comes on, the charge is good, etc. however the air is lukewarm at best coming from the AC vents. Even on a cool night with the "vent" on and AC off it is warm. It seems to me that it is a heater control valve not closing or something. I looked it up in alldata and couldn't find one though. What should I look for? Thanks.
Joe

DaleClark

iTrader: (55)

You may be low on freon. You can get the freon low to the point where the compressor will still kick on, but it's REALLY hard to get any cold air blowing out of it. Pretty much any AC shop can hook a gauge manifold up to the car and tell you in 30 seconds if the freon is low.

Hands down, freon leaking out seems to be the #1 AC problem on a 3rd gen. Actually, same with the 2nd gen.

Dale

kwiktsi

No, the charge is good- it has been checked . It even blows warm air with the vent on also. It is like the heat isn't shutting off, even with the dial all the way on cold. That is why I was thinking it is a hater control valve or something. Thanks.
Joe

darkside7

iTrader: (12)

what is your high side pressure?????

kwiktsi

I would have to hook it up again to tell you- I brough it to my uncles garage in CT and he looked at it. I live in Albany, NY . Like I said, the problem is there even with the AC off and just the vent on- on a cool night- so there is heat coming through still .
Joe

DaleClark

iTrader: (55)

I'm not totally familiar (yet) with the FD's mode control and heat control system. Most times there's a motor under the dash that moves a flapper door - the flapper door goes between air from the heater core and air from the AC evaporator, which also lets you set the temperature. There should also be a mechanism that enables and disables water flow through the heater core so there's no or little flow with the heater off.

Might be worth looking up under the dash while you change the hot-cold selection on the AC controls and see if you can see stuff moving. The air control may be getting jammed up somewhere.

Also, run the AC at full blast and feel the underside of the evaporator - it should be on the passenger side of the dash to the left of the blower motor. You should feel the unit itself running cold.

BTW, with recirc on (drawing air from inside the cabin) you'll have the coldest AC output. The idea is to pull cooler air from the outside when the cabin is SUPER hot (like sitting in the sun on a hot day), then switching to recirc so it pulls already-cooled cabin air through the system.

Could also be something dumb like a bunch of leaves or crap stuck in the evaporator under the dash limiting its efficiency.

Dale

pomanferrari

iTrader: (1)

There is a door operated by a motor. Could be a blown motor.

kwiktsi

Thanks. Is there also a valve in line with the heater hoses to control the flow too? I will look around later. All the lines get cool, everything is working but the air inside is staying warm . Thanks.
Joe

xstacy7

Off the subject, but a quick question. How do you get the old freon out of the system to install a new compressor? Do you have to have a shop do it or can you do it yourself? Thanks

Jack

kwiktsi

You need a recycling machine. Basically, it gets sucked out, filtered and put in a tank. When they need to recharge the system, it goes back in.
Joe

Tenacious

clean the coils =P

Tenacious

Also you need license to get freon, I dont really know the specs on an RX7 compressor, but generally speaking you should be around (200-215(highside) and around 50ish for low side, trick is, when you fill the compressor, you gotta do it fairly quickly so the compressor doesnt lock up.

Tenacious

Also for recycling freon, you need guages , and an empty tank, just try not to mix freon, I'm thinking your car uses R22, in high amounts of inhaling, you can get a heart attack, just be careful.

Tenacious

They never put freon in a new compressor, its alway nitrogen, you use a plug and play vaccum(made for hvac) it pulls out old freon, and creates a vaccum for the new freon to be replaced. k sorry for the spammage

xstacy7

Isn't R22 a home refrigerant? You probably mean R12.

Is evacuating the A/C system something I could do by going to Advance to get some tools?

mad_7tist

no you need some special tools like a manifold gague set and a vaccum pump to realy service any ac parts.

when you start the car cold does the air coming out of the vents seem cooler then when the engine is hot? you are sure the fans are coming on? do you have a sight glass on your reciver drier? is it clear or cloudy when the ac is on? it does sound like a diverter door prob though

J.S.J

A lot of the statements about the air temp etc over the net are subjective. The system in question (A/C) does show things to us from under the hood. First off the compressor should be coming on as well as the cooling fans. From that point with the blower turned to "high" and raising the rpm to 3K the compressor should stay engaged. IF it begins to cycle off and on the system could be low in R12. With the engine at 3K the condenser should be getting hot as well as the compressor. I know they can be hard to get to but the inlet line to the evaporator should be cold. All this should happen not withstanding whats going on with any heater issues. If the compressor cycles too much or the other temperatures are not present your A/C system is skewed.

kwiktsi

I am aware of this, the AC compressor comes on as it should and does not short cycle at all (I *used* to do AC work years ago in FL, so I have the basics covered already ). That is why I was leaning towards a heater control valve or whatever else the system uses. I honestly have not gotten to the lines to see if the high gets hot and low gets cold though, I didn't feel like digging around for them, but I will give that a shot next just to be sure. Thanks guys!!!
Joe

Herblenny

iTrader: (13)

Thats what I would do..

Shut off the AC, turn on the heat and see if hot air comes out.. If it does and when you turn it down cooler air comes out, than its not your temp control.

Are you positive that your ac clutch is engaging??

kwiktsi

Yup, clutch is engaging and staying engaged throughout the RPM range (within reason, I haven't revved the snot out of it to see if it stays running at WOT @7000 rpms ). If I put it on heat, hot air comes out, then as I turn it to cool, it stays the same from warm to cool.
Joe

cletus

This sounds similiar to a problem I had a while back. For me, it ended up being the motor that controls the mixture of hot/cold air just got stuck, probably from sitting around too much. Shop took it out to test it, saw it was fine, were confused, but when they reinstalled it, everything worked again and has be fine for almost 2 years now. Hopefully that is it, because it is a cheap fix, even if the motor itself is dead.

The shop that was working on mine said there was also a sensor buried somewhere deep in the dash that is sometimes the culprit and that was what they were going to try after checking the motor, but they said it is a real pain to get to. I don't know any more about that part though.