The A/C in my car has not been blowing as cool as what I have come to expect out of our domestic cars. It's blowing about 54 F.
Looking at the sight glass I noticed that there where bubbles flowing by so I guessed that the charge may be low. When I hooked up a tank and some guages I read approx. 30psig and around 260psig. This is higher than I expected. I suppose it had been overfilled but when I added some R-12 the cloudines in the sight glass went away. A little while later the pressures on both the low and high side started fluctuating (+/-5psi) up and down in unison about once per second. I still have no condensation on the suction line.

1. If the system is overcharged why was I showing bubbles in the sight glass that went away with more charge.

2. Has my expanion valve failed or is the expansion valve adjustable?

Did you give the system time to stabilize before charging according to the sight glass.

I expect your trouble is that the recirculate mode is not working. To troubleshoot you need to do two things. Start by removing the glovebox and disconnecting the vacuum lines from the manifold one at a time and put about 3 inHg on it with a mity vac and see that they hold vac. I expect that numbers one and two will not hold vac. This means that the vacuum pods are leaking and need to be replaced.

If all your lines hold vac then you need to turn to the diagnostic connector near the battery. Information can be found in the thread that I started a week or two ago called "At least the evaporator is not leaking." THere are links in there that will tell you how to use the X11 diag connector.

Good luck,

Someone in the thread mentioned about air not blowing through the center vents (forced through while driving) when the system is off as being an indicator of the recirculation flaps working. I'm guessing that when the system is turned off that the recirc flaps close. Does this sound about right?

Sure hope it's not the pods. Incidentaly, evaporator failures are unheard of in my neck of the woods. Must be humidity/use dependent.

I also hope its not your pods, but it is likely. It will only take you about 20 minutes to check them. Don't apply over about 3inHg. during the test.

I just got my set of new pods from the Brown Truck today. I am making my LED based tester for the diagnostic port tonight. I want to check that before I start tearing apart the dash. If I have another problem I want to know about it first. I'm not too keen on the idea of having to take off the dash twice.

If you're using your a/c at all, whether at the equator, or at the North pole, your evaporator can still fail. I don't think that you have to worry on your car, due to your pressures. It doesn't sound as if you have a leak anywhere. I would be willing to bet, however, that if there are 124 cars in your area, then there are 124 cars that have lost their evaporators.

Best of luck and keep us informed,

I was under the impression that the evaporators fail due to external corrosion from condensate. I believe that the aluminum is pretty inert with respect to R-12.

I searched for X11 diagnostic port but could find no link with A/C. Is this the port used for CIS diagnostics? What window into the A/C system does it provide?

It's my understanding that the problem on the evaporators is the reaction between the copper and the aluminum that the OEMs are made of.

__________________
2012 E350
2006 Callaway SC560

Brewtoo mentions the bimetallic corrosion. It also could be the fact that these two metals expand and contract at different rates, eventually resulting in separation.

Either way, the failure rate has nothing to do with condensation, OR R12 flow.

The X11/4 connector is on the barrier that separates the engine compartment from the battery compartment. To learn more information about this, look for my thread asking if there is a substitute for the impulse counter. Just search the Tech Help Forum, Titles Only, for Impulse Counter.

I built an LED counter today. You will find a schematic for it in one of the threads or links in the above thread. The climate control computer stores trouble codes. The LED allows you to check for and draw these codes if any are present.

I wanted to make sure I had no other problems requiring any other parts to be replaced while I have the instrument panel off. Luckily everything was clean. I received my pod set today and I expect to start the project Saturday. We had our first 100 degree day and my shop is not air conditioned. I am going to sweat my you know what off doing this.

Good luck with yours. Have you removed the glove box and tested your vacuum pods yet?

Have a great day,

No, I will do so this weekend. Your kind of temperatures are not imminent up here so I'm in no great rush. I checked to see if the air stopped flowing through the centre vents when I'm driving when I turn the system off, and it does stop. Whatever that means.

I checked while driving yesterday and the air temp went down to 49F at a steady 2100 rpm. Is it reasonable to expect low 40's ?


P.S.
Found the thread. Thanks!

Yes indeed. If the air is being recirculated, the vent temp should get down to about 40 or 41 F. If it goes below that, it also indicates a problem.

What is the outside temp when you get it down to 49?

Since you do not get airflow with the system off that means that the system may not be stuck in fresh air mode. I would check all the vac pods anyway. The car is old enough that there could easily be one or more leaking from age.

Let us know what you find.

Outside temp was 82F.

I still don't think recirc vs. fresh is a big factor.

Yesterday it was about 95 degrees here, dewpoint was 73 and my 124, NOT on recirculate, was putting out an almost uncomfortable 42 degrees.

__________________
2012 E350
2006 Callaway SC560

Brewtoo,

Your system automatically puts it in recirculate mode most of the time whether you hit the recirc button or not. I've been all through this in the last few weeks in the course of diagnosing my system. Two weeks ago I would have agreed with your hypothesis, but I have since learned differently.

By the temps you listed, if it were not recirculating that means you were dropping the temperature about 54 degrees F. That is all but impossible. A typical drop from a properly operating a/c system is about 40 degrees if its really working good.

89300ce,

With outside temp at 82 and vent temp at 49 you are dropping the temp 33 degrees. That's not too bad. This assumes, of course, that the system is bringing in fresh air since we have yet to confirm that your system is recirculating.

Have a great day,

Last night I checked the pressures again. This time I had a garden hose mist some water onto the condensor as it was running. Pressures where still high all the way around so I started pulling some out of the high side until the pressures seemed about right. The pressure cycling stopped (high pressure cut out?). I took it for a drive and the temps dropped to 44F with the fan on high. With the fan in auto-mode temps dropped to 39F. as the fan speed came down. Problem??

As Larry suggested in his first post, I guess I didn't let the system stabilize long enough.

I'm still going to check the pods because it seems recirc doesn't work. Wether I fix it will be another story. Lookin at the service cd I can't quite make out where the return air gets back into the fan plenum. It looks like the openings are under the dash at the firewall, at the extreme right and left sides of the air system. Can anyone confirm?

The recirc flap is part of the big black HVAC box that occupies the entire center of the car under the dashboard. That particular flap is roughly in line with the firewall, and runs the entire width of the heater box - about a foot wide. It is operated by two vacuum actuators, though there is only one flap.

It's possible to see a small portion of the recirc flap by removing the glovebox. Look past the pink vacuum actuator on the left (that's the defrost pod, BTW) more or less parallel to the firewall. You can see the rightmost bit of the recirc flap - most of it is blocked from view by the HVAC box. Try starting the car and switching the climate control between fresh and recirc while in the EC mode. You should be able to see the flap move. Better yet, get a mityvac and test each of the seven vacuum lines you see - this will tell you what works and what doesn't. All seven should hold vacuum. I recently suggested Larry perform this test, and have now caused him to blow his entire weekend pulling the dashboard out of his 300E.

You can also see the recirc flap by pulling the blower motor, but that's a bit more work...

- JimY

Hey Larry, I've been thinking about your situation with the outlet temps higher than they used to be.

I was wondering, does the temp stay higher than before even in the evening with the fan on low??

__________________
2012 E350
2006 Callaway SC560