All of the displays on my car are set to fahrenheit. I was trying to trouble shoot my A/C system. When I press and hold the "Rest" button on the climate control, I get a 1 and another number which is supposed to be the temperature of the interior of the car. Is that temp display in C or F? Thanks.

 

i dont think we're able to give you a response with certainty with the minimal
info you've provided about your car. but if you post the remaining diagnostic
data, we could probably make an educated guess. seat of pants would suggest ºF

 

Instrument cluster is programmable and independent of the CCU. CCU is metric -- Celcius (temp) and bar (pressure).

 

Thanks Richard.

 

Plutoe, as I said in the original post everything on the dash displays in F. The dash read out for the exterior temperature is F. The climate control is in F. So are you saying that the interior temperature ("Rest" for >5sec) is also in F?

 

my USA marketed E320 definitely reads ºF maybe I have a collectable vehicle

 

Mine is a 98 like the OP's. Maybe it was changed in 99 or maybe it can be switched via SDS like the cluster which would explain everyone's comments.

 

prolly. that's kind of why i asked for the OP to post the rest of the figures from the
diagnostic test...afterwhich the answer would be obvious as it depends on the setting

 

I finally had a chance to run all the diagnostics on the climate control unit.

First I checked for trouble codes. It listed 3 codes. 231 (ECT sensor), 234 (Sun sensor) and 235 (Emissions sensor). I cleared the codes and drove it for a day. Then I checked climate control displays. The dash displayed 93F external temp, the engine coolant temp gauge showed about 85-90C and the climate control was set to 72F on the right and left sides and they were on "Auto". I got the following readouts:
1 36
2 40
3 36
4 33
5 64
6 91
7 09
8 47
9 04
10 2.0
11 4.0
13 3.6
20 0.0
21 06
22 00
23 00
24 13.3
40 71
41 34
42 72
43 152

After that I checked to see if any DTC's had showed up and there were no trouble codes displayed.

I also checked to make sure the interior temp sensor fan was working and I put a small piece of paper over the intake side of the sensor vent and it stayed in place. So that seems to be working.

So this is what my car is doing. If it is cool outside (mid-high 70's) the A/C works almost normally. Cold air out of both sides but there is considerably more volume and obviously much cooler air out of the right side. I made a short trip the other day. When I started the trip it was in the high 70's outside. When I arrived at my destination, the outside temps were in the mid-high 80's. The A/C worked the whole time. Under normal conditions when I start the car and it is that warm (mid-high 80's) outside, I get barely cool air out of the LH vents and a relatively low air volume. I get nice cold air out of the RH vents with normal air volume. Within a few seconds, the air on the LH side gets warm. The air stays cool on the RH vents for about 4 minutes and then gets warm. Help. Please.

 

Thanks Plutoe. I'll check that. I have a friend who specializes in Porsche repair and he has the complete recovery system. Would low freon explain the large difference of air volume and temperature between the right and left sides? Or is that another issue that I need to address?

 

If, on my car, I change the display in the instrument cluster from C to F...the temp in the CCU also changes from C to F. So, all displays should be the same scale.

 

The UK is metric (except for speed and distance ), I don't live in England though...but another of the UK countries.

Anyway, there is no choice. I can change the display on the instrument cluster to F or C. The CCU follows what is set on the instrument cluster and cannot be set independently.

Also, when the IC is set to F or C, the diagnostic values will also be in the same value as set on the IC.

Remember...my car is a facelift.

My speedo is in MPH (with a second scale inside showing kph). I have a digital display in the IC which can display MPH or KPH as I see fit.

 

Well Plutoe, you were right on the money. I took my MB to my friends shop where we recovered 1.10 pounds of R134 from the system. We vacuumed the system for about a half-hour and installed a hair over 2 pounds (950 grams) of R134. When we started the car initially, I still noticed obviously colder air out of the RH vents. Checking with a laser temp gauge showed about a 7 to 8 degree difference. However, when the system finally got cool it reached the same temperature on both sides. Actually it is cooling better now than when it was serviced after an evaporator replacement, 2 years ago. It might not have had a full charge at that time. But I am still concerned about possibly loosing freon. I used a sniffer to try to find a leak but didn't detect anything.

Thanks for the help. Having a working A/C was really nice today since the temps were in the high 90's. Whew....

 

If you would, run the actual value test again and post the numbers. I am trying to understand the ratios of 5,7 and 8 from a non functioning system to a functioning one. I know what the numbers should be once the system is functioning, but not from a non functional to a functional system. Thanks.