Another Miata A/C problem

[black roadster]

System is R-134a.

Symptom:

On these really hot days the air blows warms and cold on the freeway. It also blows warm sitting in a drive thru.

System seems fine at cooler evening temps and on surface streets.

What's not a problem:

Checked Freon level and it's good.
Cooling fan comes on when the A/C is on.
Engine temps are good.
No unusual noises

Any recommendations or suggestions for a good aAC shop on the east side?

[Radio-Active]

Did you bypass the heater core?

That might help get the hot water out of the cabin and thereby keep the A/C cooloing better.

[POS Racing]

Just a heads up it's really hot outside, so the a/c is working as hard as it can to give ya all it's got.

Another thing to check is the vent temperature. Don't forget these words of wisdom from the past.

IIRC, the AC can only remove so much heat from the air going across the coils. It seems that the maximum amount varies based on the refrigerant, but let's say it is 30 degrees.

When it is 80 degrees outside, that means the air coming out of your vents would be about 50. If the ambient temp is 105, the vent air will be about 75. Stick a thermometer in your vent and see what it says...

Wait till the temp drops in the 90's and see if the symptoms remain.

[Radio-Active]

Very true, POS.

May I suggest painting the car White?

[Darron65]

Can we assume the top is up and you're in recirc mode?

[black roadster]

Can we assume the top is up and you're in recirc mode?

Yes you can.

I plan on taking it to an A/C shop once we can afford it.

This has nothing to do with the extreme temps as the A/C blows hot and cold with in minutes of each other.

[Sharpie]

Sounds to me like you're low on freon and the compressor is turning on and off trying to keep it from killing itself.

[Titus]

Sounds to me like you're low on freon and the compressor is turning on and off trying to keep it from killing itself.

I put a gauge on it with the plan of adding freon last Wed night... It actually read over-full in the warning range, so we didn't add much at all.

[channelmaniac]

I put a gauge on it with the plan of adding freon last Wed night... It actually read over-full in the warning range, so we didn't add much at all.

Sounds like you need to rebalance it - too much freon isn't good either.

[Titus]

Sounds like you need to rebalance it - too much freon isn't good either.

That was my first thought to, but he said it had never been recharged. I have never heard of a system building pressure over time.

[Adam Payrot]

Did you look at the "bubble" on the drier to see if it had bubbles in it?

You should be able to see it if you look through the "hole" that's about fist sized on the core support, passenger side.