99 clk 320 air conditioning

[capcon 777]

my ac blows cool air then goes to warm. no fault codes detected, freon is all there. can anyone help.

[Benztech]

Sounds like a bad evaporator temp sensor its mounted on the left side of the heater box just above gas pedal,pointing towards passenger side.Best thing is to monitor the actual value with a das tester its probably showing 100 + deg f and shutting down the a/c .When it should register about 38 deg f with max cool. Tim

[Matt L]

Doesn't that car offer a current-sensor mode to the climate-control pushbutton unit? That removes the need for the specialized tools to check the value.

[capcon 777]

thanks i will give it a try.

[Benztech]

Heres how to pull codes thru control head:
Ign. on- left temp hi /right side low setting

key off then on and within 20 sec's push the rest and ec buttons at same time,and hold for >5 secs.

The recirculation button should flash and display should show errors!
push the auto button repeatedly to retrieve all faults.

To clear codes hold down both auto buttons. Tim

[Matt L]

That one also shows the current-sensor values, right? Is it also the REST key for >5 seconds for this?

[capcon 777]

the only error code that i got was b1422 series interface. does that have anything to do with my ac. thanks agains gentlemen.

[Benztech]

Thats the link between the a/c contol head and instrument cluster.As the cluster recieves signals from Engine control about engine speed and coolant temp its sent to the a/c head.Its not uncommon to see that code.
One more question cooling fan is operational?

[capcon 777]

yes

[capcon 777]

recieved evap. temp. sensor and will install tonight. im pretty sure thats my problem do to the value codes on my car and all the great info you get on this site. thanks again and i will let you know my outcome.

[capcon 777]

i changed evap. temp sensor but it did not solve all my problem. get cool air then goes back to warm and then cold again all in 2 to 3 minutes. value codes 1- 87,2-91,3-75,4-75,5-64,6-186,7-48,8-105. no fault codes, im thinking im missing gas. any takers thanks

[capcon 777]

checked gas its all there ,next step mercedes dealer to take it in the chin . im sure they will say its the compresser. thanks guys.

[capcon 777]

ac blows cold then went to warm, just got back from dealer they said its the compressor and my drier, i had no fault codes,cost me 120 dollars to find out the problem and now i will do the work myself.

[marvinstockman]

Check the air gap on the clutch. If it is too large, say above 0.030", it might engage, and then fail to engage again because the magnet field, when the unit warms up, may not be strong enough to pull the plate in. You could monitor the voltage to the clutch with a voltmeter, and determine if it's getting voltage.

If the air gap is too large, it's fairly easy to remove a washer/spacer to bring the gap in spec. I think I posted here as 'Lazy AC'.

[capcon 777]

comp. changed all is well. nice and cold.