Hey all, my '91 740 is in need of a evaporator replacement. I tested for leaks today and found that freon is leaking out of the evaporator. The only thing I have replaced in the air box is the blower motor (and that involved only removing the screws to the mount that hold the computer in place and take the three screws that hold the motor in).
I have no earthly idea on what I need to do to remove the evaporator. Any help is appreciated.

 

pretty sure that requires ripping the whole dashboard and center console out. while you're in there, considering doing the heater core too as your old core is 24 years old, and they fail eventually.

 

From what I have read so far, it doesn't look as bad/hard to do. I have replaced one on a PT Cruiser (car really sucked from the factory anyways) and it involved tearing the entire dash apart like removing the radio, instrument cluster, center console, steering assembly, climate controls, glove box, speakers, ect.

 

I had a heater core go in our 89 740. After looking at the job I decided to take it to a local Volvo mechanic. It took him 2 days to pull the dash and replace the core. Cost $1000 and although I do most of my own work including engine rebuilds I didn't want to tackle this. Good luck

 

Ok, I don't even have $100 to spend on someone else to do the work. I have my own tools to do the job and have access to A/C equipment. All I need now are instructions on how to remove and replace the evaporator. Might as well do the heater core while I'm there.

 

note as you read how-tos, a 1991/92 740 has more in common with the 940, in fact they are identical to the early 940s.

at a bare minimum, you'll need to remove the glovebox, passenger knee bar and most of the center console. its probably easiest to take out the whole dashboard.

I do have some parts diagrams of the airbox and stuff.... err, wait, no, dayum, they are all 960/940SE, which has a whole different HVAC system.

 

I got ya so good luck as you are in for a great adventure. Keep us posted.

 

Just an update. I managed to remove the evaporator after a few hours of work. It wasn't that hard. The only difficult part was removing the many screws holding the lower part of the air box on, some being difficult to locate. Still need to replace the heater core though.
My current issue is figuring out how to remove the panels on the side of the center console and the aftermarket radio.

 

Ok, managed to remove and replace the heater core today. My only set back is that I did not make a note of where the four vacuum lines went. They are color coded at least. I have a red, yellow, clear and blue (if I remember correctly). Any ideas where these all go for the three actuators?

 

Really need help on identifying the actuators for the air box behind the heater core. I disconnected them like an idiot without taking notes of where they went. There are three actuators on the driver side of the airbox. From what I have found is that the four color lines are red, blue, beige/clear and yellow. All I can find out about the locations is only for the automatic climate control;red being vent actuator, beige being bi level actuator, blue being defrost actuator and yellow the floor actuator.
Really, really, really need help on which actuator is which.

 

digging into my VCOA DVD, there's a greenbook on "700/900 Climate Units 1982-", lets see what it says...

hmmm, it only appears to go up to 1988, and describes three controllers, 'standard heater' (no A/C), "Combined Unit + AC" with two horizontal sliders and a fan ****, and "Automatic Climate Control" (also with a slider for mode, plus a temp 'wheel'

I know my 92 has big ****/dials for fan, air mode, and temp, with pushbuttons for recirc and AC disable, I assume the 91 is similar.

wait, I *found* it "MCC" in a different version of the greenbook. it appears the color codes are the same for CU+AC and MCC+AC.

wait, the newer book only shows the layout for the 960 ECC system :-/


anyways.. from the older book

orange = recirculation shutter
light brown = lower flap, panel vents
red = upper shutter panel vents
yellow and blue go to floor/defrost shutter.
violet = source vacuum
grey = heater/water valve

naturally, NONE of these books seem to show which bellows is what, so you're going to have to figure that out the hard way. the recirc bellow is over by the fan, while the upper and lower flaps are between the heater and condensor.

 

Ok, managed to figure out the line placement. I put most of the car back together today. All I need to do now is place in the new evaporator and test for leaks.