A/C questions, anybody has some Infos?

[AndyA6]

So the summer is here and so is the heat, today another 100 degree day!

My A/C seems a bit weak.... No bueno!

Left dash side blows cold, not great but. Center left very little, center right a bit better, right side dash almost no cold air.

What can I check myself here?

Maybe one of those 134 R cans and refill?

Any tips?

Thanks!

Later,
Andy

[JFP in PA]

Originally Posted by AndyA6

So the summer is here and so is the heat, today another 100 degree day!

My A/C seems a bit weak.... No bueno!

Left dash side blows cold, not great but. Center left very little, center right a bit better, right side dash almost no cold air.

What can I check myself here?

Maybe one of those 134 R cans and refill?

Any tips?

Thanks!

Later,
Andy

If one side is blowing cold, the AC system has all the gas it needs. More than likely a problem with the mixing flaps in the heater box under the dash...........

[Heiko]

Might be a slow leak... I wouldn't just add refrigerant... the proper way to fill it is to drain what's left and then recharge it based on the exact weight it calls for. Any garage that does AC service with a proper charge station should be able to do this for you. I think the total amount required is 855grams or 30oz....

[Topless]

Originally Posted by JFP in PA

If one side is blowing cold, the AC system has all the gas it needs. More than likely a problem with the mixing flaps in the heater box under the dash...........

This^^

There is a repair tutorial on renntech that details how to repair mix flaps without dismantling your dash. Check it out.

[AndyA6]

Thanks guys! Looks like my weekend project

[thom4782]

The fact that you get different temperatures at different vents is strange. I assume that you checked that the vents are fully open and have similar volumes of air coming out of them. Given the geometry of the air handling system, the temperatures at the outlets should be very close to on another.

The AC outlet temperature at the vents should be something like 40 to 60 degrees when the system works properly. If its not in that range, then there could be several problems. One, the R134a refrigerant is too low and the system needs recharging. Two, the AC compressor has given up the ghost. Three, the mixing flaps in the heater box are allowing too much hot air to be mixed with the cold air.

My guess is that you are low on refrigerant. I suggest recharging the system before you open up the hood, remove the heater core and attempt to fix the mixing flaps. If it was a mixing problem, I'd expect the temperature to be warm and the same at all the vents.

[Topless]

Originally Posted by thom4782

The fact that you get different temperatures at different vents is strange.

Not unusual at all on a 986/996. When the mix flaps fail, sometimes chunks of foam will clog part of the vent system causing this exact symptom. It doesn't always happen this way but it does happen often. Visual evidence of foam bits flying out or found lodged in the vents is good confirmation of failed mix flaps.

[thom4782]

Good point Topless. If that is the case here, then there are really two things to fix - 1) R&D the flaps and 2) remove any pieces of foam that may be clogging the vent lines.

[AndyA6]

Hmmmm, good points. I think I will look at/check the flap, as mentioned above, good write up on Renntech, seems easy enough. Although I do not have foam flying out the vents. Also, my compressor is making rather louder than normal noises. Overhaulin' time!!

[Ian c]

Have you got dura metric ?
You can test flaps etc in the ACTIVATIONS section of the AIRCON file
I was playing with mine this week

[AndyA6]

Hi guys!

Soooo, long day today, 104 F and my garage was turned into the shop for today. I took the heater core out and checked the flap. The foam stuff is 100% fine, all present and in good nick.
Took me 1.5 hours to dis-assemble, no problems. Glad I did this so now I know that this is not the problem.

Ok, off to Autozone and bought a can of 134, checked on Pelican tech articles the needed pressure. Well, pressure was at 23 psi..... Got it up to 42 psi. Took no time at all. 37 bucks ain't too bad.

It seems cooling got a lot better! I still want to check after a days work when the car baked in the sun.

I get back later with a follow up.

Thanks for all the tips

Andy

[thom4782]

Great news. If your system is old, then it's reasonable that you were low on refrigerant and it might stay cool for years.

It's also still possible that you have a leak. If the system loses it ability to cool in a few days, the leak is large. If it takes several weeks or months, the leak is likely small.

By any chance did the bottle of 134a include UV dye? If so, you can buy a cheap UV light to look for dye. If you find dye, that's were you'll need to replace a component.

If you didn't put dye in the system and it looses its ability to cool, you've got two options. Take it to an AC shop and have them use a sniffer to detect leaks. Or, you can refill again with 134a that also contains dye and look yourself. There's a trick to look for dye in the evaporator. Pull the drain hose and look for dye inside the tube.

Hope you've got it fixed and you wont need to do anything more.

BTW: if you have a meat thermometer, you can put it inside the vent to see what outlet temperature you're getting. It should be 45 degrees or less.

[AndyA6]

Small update:- air is cold! I think the "recharge" worked. It made the compressor run quieter as well. Next step, thermometer.

[thom4782]

Here's some data from my car today. It's 84 degrees outdoors today where I live in CA and the humidity is about 50%. When driving my car on the highway with the AC set at maximum, the center vent outlet temperature is 40 degrees. When driving in traffic with the same AC settings, the center outlet temperature rises to 45 degrees. If I set the car temperature to 68 degrees on the AC control unit, the center outlet vent reads 50 degrees.

[AndyA6]

Just a few pics from last weekend. I checked the "flap" to see if the foam is still there (it was). Not so difficult of a job.

As mentioned earlier, a quick recharge solved my issues, blows on low at 38!

[Topless]

Good work and follow through Andy. If refrigerant was low there must be a leak somewhere so pay attention to it for a while. Mine got low after I changed out a damaged radiator and I left the condenser coil hanging for a few days while I sourced the part. I suspect this stressed the connector o-rings but once bolted back in place the leak stopped. Like you my mix flaps were A-ok but I have seen a bunch that weren't.

The process of elimination works.

[AndyA6]

Thanks! Honestly, I'm quiet happy I've done this work.
I just love a bit wrenching.

[AndyA6]

I hope this will help as well........ Unbelievable amount of crud!