strange air con problem

[madtek]

Hello,
newbie here
May i ask if there's air con experts around here ?

the situation is:
when it starts, during the first 5-10 seconds the "High port" pressure rises steadily up to the limits of the manifold gauge (~400psi ) then I just switch it off to be safe,
also the condenser gets very very hot during this, (can't even touch it) as for the air in the car, it blows cool air (~10-12C) for that 5-10 seconds then starts to get warm

outdoor temperature during the test is around 20-25C .
Low port stays around 30-40 psi during the test.
Static pressure (when the car has been off for a while) is around 80psi on both ports

So the question is: what could be the cause of that massive rising pressure in the hight port ?

Pressure sensor fault? that keeps compressor pumping it up?
or maybe expansion valve fault ?

my car is mercedes c220 2003 , i believe it has clutch-less compressor , it spins all the time

any help much appreciated! sorry if my english is bad:bannana:, (not my native)

p.s.
tried to reset A/C settings on the climate panel already, didnt help

 

[npuk]

Where in London are you? If you want to get it checked out I can highly recommend Alpinair at Hanger Lane. Vehicle Air Conditioning. Air Conditioning Installation and Maintenance Service, UK - Alpinair

 

[fisheggs]

Do the fans fitted to the condenser come on when you turn the A/C on?

 

[madtek]

Thanks npuk, will check them out

 

[madtek]

Do the fans fitted to the condenser come on when you turn the A/C on?

mmm, there is one big fan behind the "sandwich" of a/c and coolant radiator, and it doesn't start when the a/c is on,

should it start spinning?

 

[fisheggs]

If the pressures are going as high as you've stated, with A/C fans not engaging and compressor not cutting out, then I would point to the pressure switch and its wiring.

The compressors on these and mot A/C systems have clutches which are operated by the presuure switch and control module.

Have a look at the connector block to the pressure swich and check fuses and basics 1st.

 

[madtek]

If the pressures are going as high as you've stated, with A/C fans not engaging and compressor not cutting out, then I would point to the pressure switch and its wiring.

The compressors on these and mot A/C systems have clutches which are operated by the presuure switch and control module.

Have a look at the connector block to the pressure swich and check fuses and basics 1st.

Thanks,
I'll have a look closer

 

[npuk]

You can check if any fault codes are stored for the AC and delete them using the climate control panel. There it a button combination you need to press. If you so a search on here you should be able to find it.

 

[madtek]

You can check if any fault codes are stored for the AC and delete them using the climate control panel. There it a button combination you need to press. If you so a search on here you should be able to find it.

yep, did that , circul. button with defrost for 5 seconds, they blinked for about 30 sec, (but i couldn't see any fault codes , my climate panel is analog, doesn't have led display)
, tried it several times , didn't help unfortunately