Defrost fogging up car

[Mike Stitzer]

Last night no matter what fan setting I had I could not get the car to not fog up inside. Reminded me of my old Topaz that had a leaky heater core. But this doesn't seem the same as there's no coolant smell inside. One time last night the car all of a sudden did defog, but then a minute later instantly fogged up again.
For some time now the A/C compressor has been kicking on and off constantly, every second or two. Now it doesn't seem to be doing anything at all. Could that be the problem? But does the compressor have to be on to effectivily defog the car?

Mike

 

[DHMag]

does the fog smell of anything ? first guess is heater core. but since you say you dont smell it, my second guess is leaking evaporator, freon getting into passenger cabin. constant A/C cycling indicates low freon level. correct A/C cycling is needed for correct defrosting. however, it is not required for defrost.

 

[Blue-By-U]

I can't help you diagnose a mechanical problem here, but I can suggest a product called Fog-X. It's from the makers of Rain-X and is an anti fog glass coating you apply to the inside of your windshield. It works very well and you can find it an any automotive shop or local Walmart.

 

[Mike Stitzer]

Blue-By-U:
I can't help you diagnose a mechanical problem here, but I can suggest a product called Fog-X. It's from the makers of Rain-X and is an anti fog glass coating you apply to the inside of your windshield. It works very well and you can find it an any automotive shop or local Walmart.

Yeah I have used that stuff on the inside of my motorcycle faceshield, but shouldn't need it for a car.

It's due for inspection so I might have them check the refrigerant level. Hopefully it's as simple as that.

Mike

 

[sdpatt]

The rapid cycling of the A/C compressor, as DHMag stated, is due to the low pressure in the refrigerant system. You need to recharge the R134a in your system to the proper level to get correct functioning of the air conditioning portion of the climate control system.

The DEFROST setting on the climate control directs the fan's output to the dash registers to present the airflow to the front windshield. It is the responsibility of the evaporator, properly chilled by the refrigerant system, to remove the moisture from the air.

Without the de-humidifying effect from the ice-cold evaporator, the warm air directed to the glass will result in the moisture condensing into fog in your line of sight. Charge the refrigerant and clear your glass.

 

[SHOZ123]

My bet is it's coolant. Try tightening the hose clamps on the heater hoses at the firewall.

 

[Mike Stitzer]

UPDATE:

Got the car back and the place said they couldn't find anything wrong with the refrigerant system at all. All levels were up and the pressure was spot on. Even while running the compressor was cycling on and off as it should. Any guesses?

Mike

 

[Rob94]

If the drain is clogged, the evaporator case could be filling with water from condensation. This could be causing the fog problem on your windshield. Do you notice water dripping under the car when the A/C is on? If not, I'd bet you need to unclog that drain.

 

[Mike Stitzer]

Where's this drainplug?

Mike

 

[Rob94]

Easiest to access it from under the car. About center of firewall. It'll either look like a grommet in the firewall, or some have a 90 degree hose. Gently insert a coathanger, and be prepared. If it is clogged, there'll be a lot of cold, stanky water come splashing out. Mine clogged once, to the point that condensed water was dripping into the car. When I cleared the drain, there must have been a gallon and a half of nasty water come splashing over my head. Good luck.

 

[projectSHO89]

The drain is located directly beneath the lower evaporator line.

Look for a plastic ****** about two inches below that line. Stick the coathanger end in there.

Steve

 

[Mike Stitzer]

Found something new. I was poking around and found that my passenger side floor is absolutely soaked with water. Yes, it's water and not coolant. Could a plugged evaporator drain be overflowing into the passenger compartment? I'll be looking for the drain today after work to see if it's plugged.

Mike

 

[Mike Stitzer]

New update.

didn't get to check the drain for the evaporator case, but on the way home yesterday it was raining and my car just steamed up the whole way home. Once home I popped the hood and verified that the compressor is not engaging at all. Yet a week ago the shop checked the pressure and all was fine. It was even cycling on and off as they let it sit with the guages on. Said it turned on and off exactly as it was supposed to. What else could be causing the compressor from engaging?

Mike

 

[DHMag]

damn flooding rules....lets see if i can remember what i typed the first time...

check your mechanicals first. make sure the connector is plugged into the clutch coil. check the clutch gap, should be .030" +/- .005". put the gauges on the system and check your readings against your previous readings. if they are lower, time to tear down the A/C system and replace all the o-rings. use R-134a compatible o-rings, i believe they are the green ones. but, this will just insure your A/C system is up to par, your main problem may still exist. you really need to check that drain.

 

[rangerj]

Mike,

Your wet passenger side carpet is a sure sign of your evaporator drain being plugged up. Clean out the drain.

The build up of water around the evaporator may be causing your A/C anomolie (sp). The fact that your A/C pressures are normal, and that your Compressor is cycling normally, tells me that the A/C components are working properly.

If you are getting an ice build up because the water cannot escape, then the thermister will shut down the A/C. That is a very oversimplified explanation. The point is, you need to cure the drain problem.

Your wet floor tells me that you are getting an ice build up. When you stop the car the melted ice is ending up on your passanger side carpet because the water cannot escape through the drain.

Fix the drain problem, and if that doesn't clear up the A/C problem we'll address then. rangerj

 

[Mike Stitzer]

Well I poked a coat hanger in the drain, at least what I beleived to be the drain and nothing came out. The drain was where some of you described and was a plastice short tube comeing straight out (forward) from the firewall. I could only get the wire in there about 2 inches, but nothing came out.

While under there I saw another hole around the passenger floor pan. I poked the wire up there to see what it was. Well....it was the passenger carpet. Looks like there should have been a plug in there. So that could actually be the source of the water on the floor of the passenger compartment. So we might be dealing with two separate issues. Any ideas?

Mike

 

[projectSHO89]

That hole, if it was 2-3 inches in diameter, was for the SFB bolt recall.

There should be a plastic or rubber plug sealing it.

Steve

 

[Mike Stitzer]

Well that solves the problem of the floor flooding. Now I guess the AC compressor clutch is the next thing I'll check.

Mike