2002 Cougar: Air Conditioner puts out very little cool air.

[moonjohn]

2002 Mercury Cougar
Air Conditioner puts out very little cool air.

I have been told the air conditioner is operating correctly but is poorly engineered.
Was told to put tinted windows on and to not expect the AC to cool the car until it has run for a long time.

Problem:
AC has 4 cool air vents on the dash.
From left to right, I call them 1, 2, 3, and 4.

It takes 10 minutes until fully cooled(?) air comes out.

Performance with fan set on 1(low speed) and 79° fresh air.

Vents ............ #1 ... #2 ...... #3 ..... #4

5 Minutes ...... -7° ... -6° ..... -9° ... -18°

10 minutes ... -12° ... -8° ... -15° ... -24°


If all vents put out like Vent #4, it would probably be OK.
I wonder if there could be a problem with the duct work.
I can hear the flaps moving when I switch from fresh air to recirculated cabin air.

[DeltaP]

If Ford had designed it like that they wouldn't have sold 2 of them!
What the heck are you using for a thermometer? Those readings are impossible in automotive air conditioning. Those are freezer temps!
Get yourself some proper tools and guages.... Aw, just take it to an a/c repair shop somewhere and get it diagnosed.

[moonjohn]

Originally Posted by DeltaP

If Ford had designed it like that they wouldn't have sold 2 of them!
What the heck are you using for a thermometer?
Those readings are impossible in automotive air conditioning. Those are freezer temps!
Get yourself some proper tools and guages....
Aw, just take it to an a/c repair shop somewhere and get it diagnosed.

The AC was checked out by a master mechanic who told me everything was within factory specks and that it was just a poorly designed AC.
The pressures were all fine.
I think the problem he had was that he used factory diagnostic procedures and used a glass mercury thermometer and only took the temperature in only one of the vents.

I took the temperatures with a infrared thermometer; the type typically used to measure AC temperatures.
I took temperatures every minute.
I've only show the 5 and 10 minute values because the cooling stabilized after running about about 10 minutes.

The values I show are differences in temperature between the outside air and the AC vent output
I understand that air conditioning efficiency is measured by how much the ambient air is cooled.

So in my data, when I show -7°, it means the ambient outside 79° air was cooled to 72°.

The problem is that if the outside air is 95°, the 4 vents would be putting out at best: 83°, 87°, 80° and 71° air respectively.

I suspect that something is not hooked up properly, but everything is covered up so I can't look at anything without out removing the dash.

[DeltaP]

Sounds like the blend door is sticking or broken. Dont try to complicate this. This would be the wrong application for a laser,non contact thermometer.

[kevinande]

If you have a cabin filter, check it and clean or replace it. Check for restrictions in the air path. Sometimes rodents get inside these things and build nests. Check the an itself. The motor could Judy be old and weak, or the fan itself could have crud on it preventing proper air flow. Turn it on a setting higher than 1 and recirculate the air that might help a little.

[moonjohn]

Originally Posted by kevinande

If you have a cabin filter, check it and clean or replace it. Check for restrictions in the air path.
Sometimes rodents get inside these things and build nests.
Check the an itself.
The motor could Judy be old and weak, or the fan itself could have crud on it preventing proper air flow.
Turn it on a setting higher than 1 and recirculate the air that might help a little.

I replaced the cabin filter.
Nothing is plugged.
I get a good volume of air in each of the 4 air outlets.

I tested the AC at several different condition of air source and blower settings.

I only presented the fresh air, low blower settings because I understand that is how the factory says how the test should be run.
My tests at other settings gave the results one would expect given the data I have shown.

When I drive the car, I use recycled air and a blower setting of 2.

This works OK if it is not hot outside.

The problem is that when it is really hot outside, I get warm dry air instead of hot humid air.

I tested the temperature setting dial.
When I turn it to hot, hot air immediately comes out of the vents.
Then when I turn it to cold, the cool air immediately comes out of the vents.

I have the Shop Service Manual for the Cougar, but it's difficult to understand how everything is supposed to work.

They have a schematic for the AC system showing various components of the system and how they are supposed to work but it's not very good.

It's not obvious on how one could get significantly different temperatures coming out of the 4 vents.

When the AC is 100%, a door is supposed to close, thereby isolating the heater core.
I would think that if the door didn't close completely, hot air from the heater core would leak in so that the AC would never put out fully cooled air.

But then, if I started with a cold engine, I should initially get cold air out of each of the 4 vents and then have warmer air coming out as the engine warms up.
This doesn't seem to happen.

[moonjohn]

Problem is fixed.

Took it to a good garage.
After 3 days, they had no solution.
Told me it would cost $1,000 if they had to remove the dash to get at the distribution system.
Told them to do what was required to fix the problem.
2 hours latter they called me to pick up the car which now had a functioning AC.
Solution:
They removed the freon and weighed it.
It was 1 pound low.
They put in the proper weight of freon along with oil and leak detector.
Everything now checked out fine.
Apparently there was only enough freon to cool one side of the cooling radiator.
So only the vent that got its air near that side of the radiator blew cold air.
The vents that got their air from the far end of the radiator blew warn air.
With the proper quantity of freon, the entire radiator is cooled so all 4 vents put out cold air.
Total charge: $85.

[aleekat]

Refreshing to hear about an honest shop. You need to spread the word for that shop.