Just fitted new compressor. When it was taken for gassing they said compressor was working but the system had a blockage building pressure up.

Any ideas what could cause blockage

Hi Keith,

Depends where the blockage is, but generally speaking these systems flow very well... I can only think one of the return pipes is clogged, but I dont quite know how!

The fitter has had the air line on and there is a blockage behind the Dash board. So could anyone tell me what part could be blocked behind the dash, also how do you access it as I expect part of dash board will have to be removed

Im confused, are we talking about the same systems? it sounds like you may be referring to a blockage in the heater matrix which would be tricky to work with.

I don't know much about AC either, but as an engineer i have a grounding/ deeper understanding of different systems

The part that is inside the dash is the evaporator, it sits inside the heater box alongside the heater matrix, the AC runs fully cold all the time and you adjust the temp by turning the heater up and down - the system sucks hot air out of the evaporator, and transfers it to the condenser (in front of the engines' radiator)

the evaporators' pipes go through the bulkhead in the middle, at the back of the engine bay,(on the mk3 Mondeo, other Fords are probably the same ) the evaporator is inside the heater box and that is under the dash, the dash often has to be pulled apart to get at the heater box, the heater box has to be split to get at the condenser/ heater matrix

It may be possible to unblock the evaporator without taking the heater box out, an airline could be connected to the pipes (going to the evaporator) from the engine bay side, this could be the reverse-flow from the normal (just an idea f mine, instead of pulling it apart)

I gave up messing with my AC and just removed it all (had to get a special belt, etc) saved 11kgs and a 1kg pully that always turned with the engine (even when the AC was off, so its like a lightened flywheel - 1kg ) fixed the rattling AUX belt forever, as well, bit extreeme but i figured no point in dragging the junk around if it does not work, + i dont ever have to re-gas, or worry about the AC failing