jwbeck17

Hi everyone. Usually I drive with the windows down, but today was quite hot, so I put the AC on. The temp was cooler than just the fan, but not by much.

When I got home did some checks. The blower and fan speeds are fine, when I raise the temp it gets hot and when I press the AC button I hear it engage. I checked the AC clutch and it engages perfectly. I also looked through the sight glass, but am not sure if it is telling me low R12 or not, since I haven't looked at it before. Does the flow I see indicate that the R12 is low and needs a recharge? Take a look at the video and let me know what you think.

ammonman

I couldn't get the video to play but the still shot looks OK if a little cloudy. Perhaps someone added dye to find a leak. Low charge typically shows as periodic or constant foaming in the sight. An occasional bubble is not a big deal. Is your evaporator coil clean? Peal back the boot between the blower and the HVAC housing and look at the coil. A soft brush and vacuuming will restore flow through the coil.

Mike

SeanR

Step one, ensure the heater control valve is closing completely.

jwbeck17

Does this link to YouTube work?

jwbeck17

Wait...that is too funny. I just posted the video...if you want slo-mo. I'm sure that you found it more dramatic anyway.

Posting a new one in a sec...

jwbeck17

ammonman

Looks low on charge, but to be sure you need a set of gauges and a thermometer in the center vent.

Mike

docmirror

Follow Sean's advice.

He is in TX.

He has worked on 87,656 AC problems on 928s.

Pay attention.

dr bob

That's a lot of bubbles in the sight glass,most probably caused by some of your refrigeratnt leaking out. Bubbles don't cool the car much, since there isn't so much expansion available at teh expansion valve.

(re-cue old Bob record about fixing leaks before putting in new refrigerant).


Follow Sean and Mike's advice about fixing a possible leaking heater valve, then connect good gauges and have a couple thermometers handy to see the heat balance. Then decide on a course of action.

Eplebnista

Dr. Bob:

You wrote: Could you please elaborate or post a link to further elaboration. Are we taking temps off the lines or doing something else?

Thanks

dr bob

Ambient and in-car temps give you an idea about how balanced the system is operating. Most folks look solely at the center-vent temp results, since that's what you feel when you drive. Full diagnostics of condenser and expansion valve functions need ambient temp to compare with system pressures. You can use the same thermometer for both, but they are cheap. Two gives you a look at condenser downstream temps too; I sometimes stuff a thermocouple between the condenser and radiator if I suspect the condenser is obstructed on either the air or liquid side.

Eplebnista

OK. Thanks. You also need ambient temps to evaluate the high and low side pressures.

Others may have mentioned debris blocking the evaporator. It is also not uncommon for leaves and other stuff to get between the condenser and the radiator.

jwbeck17

Finally got a chance to get back at it. Took off the air filter to get a look at the heater valve and other bits.

What I believe is the valve (black and white plastic plunger lever against the firewall slightly passenger side) looks like the lever is working properly. There may be a leak somewhere, but I'm not experienced enough to see it. I took some videos to share to see if they help identify anything. AC is on full blast. Any thoughts?

dr bob

Jason--

If it wasn't spewing hot air from the vents with the slide left, the HCV is activating correctly. Whether it's leaking by is a different discussion.

You are still running with a low refrigerant charge. (cue that darn fix it before filling it record again...) You'll need enough charge to maintain pretty much a clear liquid stream at the sight glass. Right now the pressure (charge pressuure) is too low to condense the refrigerant to liquid again. The cooling effect of the refrigerant is really the refrigerant going into the evaporaor as liquid, using the heat from the car to boil it to vapor. If it's already vapor (bubbles), then no boiling occurs and no heat is stolen from the cabin air.