No heat from heater, 98 s320

[kradovcich]

I have a 1998 S320 and just noticed the the heater is not working. Living in CA didnt require me to use it until just a week ago.

I checked and both drivers side and passagers sides, both blows cold, I raised both tempatures individually on the climate control panel. No help. Hit defrost button and it goes into full blowing mode but still blows cold.

Any suggestions where to start?

Thanks in advance.

[kradovcich]

OK, I think I was able to run an ac test by holding down the rest button. this was the results from the LED panel

1 89
2 65
3 76
4 75
5 92
6 91
7 5
8 73
9 0
10 0
11 1.9
12 1.3
20 0
21 0
22 0
23 0
24 12.0
40 5
41 3
42 73
43 136

The outside temp showed 66. hopefully this helps.

[mbdoc]

Try UN-plugging the heater valve, located behind the drivers side headlight under a plastic trim.

[kradovcich]

I re-ran the test and this is the new figures
1 95
2 73
3 75
4 74
5 87
6 172
7 6
8 91
9 0
10 0
11 1.5
12 3.3
20 0
21 7
22 0
23 0
24 14.1
40 5
41 3
42 73
43 136

Ive also tried unplugging the electrical connector to the heater valve and still no heat.
any suggestions?

[mbdoc]

The results of that test #3 & 4 are too low, most likely the heater valve is stuck CLOSED.

No coolant flow thru the heater core.

[kradovcich]

Thank Doc,

I'll pick up one on ebay.

[kradovcich]

Thanks Doc,

That was the ticket...

Picked up a valve on ebay for $132. Unit was fixed within 1/2hrs.