OMG its hot!

[dabuddha]

Well my AC died on me unfortunately last week. Please bear with me since I'm not a car guy.

I have a 1998 Mercury Grand Marquis.

I was driving down the road with my AC on and I shut it off for a second while at a stop light. When I turned it back on, hot air started blasting me. I set the temperature at 60 and it was still hot air (not outside air temperature but heater type hot air).

I popped the hood and felt the "condenser" (prolly not even the right name. It was a black cylinder that was slightly bigger than a coke can). The thing was freezing cold to touch. I then looked at the compressor (which I believe was below the engine) and I could see the head spinning. It would spin and then stop every 6 seconds. Then it would start up again and stop.

The first garage I took it too was telling me I needed freon (which I didnt think was the case since the "condenser" was ice cold.) After he saw that there was hot air blowing though, he said he doesn't know what the problem was.

I'm not sure who to take it to now (reluctant to take it to the dealer cause I don't want to spend too much if possible). Any suggestions on what to do or try would be greatly appreciated

UPDATE (06/16/2008)

I took it to the dealer last Friday and had them take a look at it and they said that the blend door motor needs replacing (Go AT!) Unfortunately, they want $1350 for the job (Yikes!)

Calling up a different dealer, it turns out the motor itself only costs $75. I called around quite a bit but I couldn't find anyone that knew how to replace the motor (Most people didn't even know what I was talking about).

On a side note, I'm not sure what the dealer did in order to diagnose the problem (prolly hooked it up to their computer to get the "error" code) but on Saturday, I was waiting for the wife and I turned on the AC out of boredom. I was struck but a pleasant freezing blast of air!. Apparently the AC started working again.

So Father's day rolls around and my 1 year old daughter got me a Garmin GPS unit. Very cool gadget and my wife really likes it since she's a relatively new driver still.

Well the reason I mentioned the GPS unit is this morning (Monday) I go out to the car and the damn thing won't start now. I turn the car on and everything seems to be working fine. The AC is working, radio runs, lights are bright so I don't think it's the battery (replaced the battery back in April). When I try to start the car, nothing happens. Doesn't crank or turn over or anything.

I'm thinking it has to do with my alarm/remote start system. I noticed that when I arm/disarm my alarm, it wasn't doing the chirps that it normally does. Plus the system does have a "kill engine" feature. When I get home, I'm going to try to disconnect the battery and reconnect it (in hopes that it might reset the alarm somehow).

*bangs head on his desk*

 

[CoachB]

I am by no means an AC repair man. I have had experience with the type of issue you describe. In my case, the system needed freon.

As explained to me, the compressor is trying to work properly but doesn't have enough working fluid to be effective. Normally, the compressor runs and builds pressure and then releases it to the system. That pressure change is what causes the cooling.

Auto systems are generally designed to run a bit, get cold, and then rest a bit. That helps increase mileage and power.

When the freon gets low, the pressure doesn't build as it should. The sensors in the system cause the compressor to run more frequently, on..off..on..off, trying to build pressure. Until the system has enough freon, things just won't work.

I would get a second opinion.

 

[dirtboy]

I know this can happen to home A/C's so maybe it happened to your car. Maybe the condenser "froze" over. Turn off the A/C and let it thaw. Don't try to accelerate this process, just let it do it's thing. Once it's thawed try your A/C again. If it fails, then leave it off and then have a shop diagnose it.

 

[dabuddha]

Originally posted by: dirtboy
I know this can happen to home A/C's so maybe it happened to your car. Maybe the condenser "froze" over. Turn off the A/C and let it thaw. Don't try to accelerate this process, just let it do it's thing. Once it's thawed try your A/C again. If it fails, then leave it off and then have a shop diagnose it.

I've kept it off for few days straight (meaning not running the system at all) but it still doesn't work :/

 

[dabuddha]

Originally posted by: CoachB
I am by no means an AC repair man. I have had experience with the type of issue you describe. In my case, the system needed freon.

As explained to me, the compressor is trying to work properly but doesn't have enough working fluid to be effective. Normally, the compressor runs and builds pressure and then releases it to the system. That pressure change is what causes the cooling.

Auto systems are generally designed to run a bit, get cold, and then rest a bit. That helps increase mileage and power.

When the freon gets low, the pressure doesn't build as it should. The sensors in the system cause the compressor to run more frequently, on..off..on..off, trying to build pressure. Until the system has enough freon, things just won't work.

I would get a second opinion.

I used to have that problem in my honda accord. The thing with that car though was the air coming through was outside temperature air. My currently car is blowing heater temperature air (meaning it feels like I have the heat turned up to 90 degrees.)

 

[exdeath]

The condenser is the large thin "radiator" that you see from the front of the car which obscures the engine coolant radiator. The canister is called a receiver/drier and should actually be warm (?) If it's cold then it's probably being depleted too fast on the outlet (ie: rapid pressure drop).

I'm not an AC expert but I would have to guess if there is sufficient refrigerant the problem is with the expansion valve or evaporator, as obviously there is refrigerant being compressed and accumulating in that canister, but it's not making it to the evaporator correctly (the part in the car that is the source of cold air next to the blower).

The compressor interval is determined by a sensor/switch on the evaporator, so if it's not getting cold it will keep working full time regardless.

 

[exdeath]

Talked to someone more knowledgeable than I am on AC stuff to clarify. If the canister is near the firewall, and is connected directly to the compressor, it's an accumulator and is supposed to be cold. If it's near the front of the car and is connected to the condenser, then the firewall, it's a receiver/drier and should be warm.

 

[dabuddha]

Originally posted by: exdeath
Talked to someone more knowledgeable than I am on AC stuff to clarify. If the canister is near the firewall, and is connected directly to the compressor, it's an accumulator and is supposed to be cold. If it's near the front of the car and is connected to the condenser, then the firewall, it's a receiver/drier and should be warm.

Thanks for all the info I'll get it looked at and I'll try to get a picture of under my hood this afternoon when I get home from work. Any idea if dealers normally give a "free" estimate or at least a set price on an estimate. I'm always deathly afraid of open ended deals where I have no idea how much I'm going to be charged.

 

[bruceb]

Have the AC tech run a pressure check. That will tell right away if the freon charge
is close to what it should be or correct. It sounds like in your case, the Hot Air
blend doors are stuck in the Hot Position (under the dash) .. This can be either a hose,
if the system uses vacuum to move the doors, an electrically operated blend door, or
on some cars, it is operated by a wire cable. If your car uses a valve to route coolant
thru the heater core, that valve could be stuck in the Heat position and cause the same
issue. The thermostat controls the cycling of the compressor, but low pressure can
also stop the compressor thru a switch in the suction line.

 

[91TTZ]

My 86 Z used to do this when a vacuum hose cracked. The AC would be working but the flaps under the dash wouldn't work, so it blew out hot air.

 

[dirtboy]

If they say you are low on freon, then you have a leak somewhere. What will happen is they will refill it, then when you run out again, they will charge you to refill and repair. Take it to a decent shop or maybe even Ford.

 

[GuitarDaddy]

That's called "short cycling" of the compressor, and it is caused by low freon.
As stated above that means you have a leak which should be addressed, sometimes an oilcharge w/stop leak + freon will get you by a season or two, but its best to fully diagnose the leak because if it is large the freon will be wasted.

 

[dud]

"The first garage I took it too was telling me I needed freon ..."

OP, you stated that you have a 1998 Mercury Grand Marquis. By law auto makers HAD TO switch from R12 (freon) to R134 (or 134a) in the model year 1994 and later. Your car should not require "freon" as that would mix refridgerants and basically ruin your A/C system.

Go have it checked by a reputable A/C shop that knows what year it is ...

 

[thomsbrain]

You guys aren't paying attention to the symptoms the OP is describing, and neither have the shops to which he has taken it. Frankly, I'm surprised.

My immediate thought was a problem with the servos or whatever moves the hot air flaps in your particular car.

Look at the evidence:

--It happened when you shut off the HVAC for a moment.
--It sounds like you have automatic climate control, since you talk about setting specific temperatures on the controls.
--The A/C appears to be functioning, judging by the components getting ice cold when engaged.
--OP repeatedly describes the air as HOT. Not "lukewarm." Not "outside air." HOT air. HEATER air.
--Malfunctioning A/C units do NOT create hot air. They just stop making the existing air cooler.


So if you're still getting HOT air regardless of the temperature to which you set your climate control, then the first culprit to look at is the flaps that control the cold/hot air mix for your climate control.

In short, if the A/C malfunctions, it will blow VENT temperature air, not HEATER temperature air. So there's a really good chance this has nothing to do with the actual A/C system.

 

[Zenmervolt]

Originally posted by: 91TTZ
My 86 Z used to do this when a vacuum hose cracked. The AC would be working but the flaps under the dash wouldn't work, so it blew out hot air.

Winner.

If the air is hot, as in heater temp, one of the blend doors has failed. In some cars they are actuated with vacuum, in some they are purely electronic. Somewhere in the vent controls, something snapped or lost vacuum.

ZV

 

[Colt45]

Originally posted by: dud
"The first garage I took it too was telling me I needed freon ..."

OP, you stated that you have a 1998 Mercury Grand Marquis. By law auto makers HAD TO switch from R12 (freon) to R134 (or 134a) in the model year 1994 and later. Your car should not require "freon" as that would mix refridgerants and basically ruin your A/C system.

Go have it checked by a reputable A/C shop that knows what year it is ...

I call all refrigerants "freon". I'm sure i'm not the only one. Now if he said freon-12, that would be a different story.

 

[dabuddha]

I did find this for what it's worth:
http://www.visteonclimatecontr...com/tsb/98103_tsbs.htm

I'm going to get it checked this friday. Just got back from vacation late last week so I didn't get a chance to yet. Thanks for all the information BTW

 

[LTC8K6]

Can the blend door produce the very hot air by itself?

I thought the valve to allow coolant to pass through the heater core had to be opened, and you only got that when you asked for hot air.

IOW, a blend door failure shouldn't produce very hot air by itself, since the hot coolant wouldn't be flowing through the heater core.

Or I could be nuts...

 

[dabuddha]

Update in the first post