AC problem: I'd just bought a 1991 240 with an AC that's been converted to R134. My mechanic replaced the AC hose that goes from the dryer to the compressor, and he recharged the system. It is holding pressure; however, the AC won’t come on. The compressor and fans are not getting power. He traced all the wires in the engine compartment and under the dash. It appears the problem is somewhere inside the dash/center console panel. Could someone please point us to the right direction as to where the AC electrical problem may be found before we start taking the console apart? This thing is so old, I'm afraid the plastic pieces on the dash/console will disintegrate when we take them off. The AC switch on the dash/console won't even come on (no blue light). All the relays and AC fuse are good. Is there anything I should watch for when we take the dash/console apart?
Brakes: Does the 1991 240 come with ABS brakes? Is there a test I can make to see if the ABS is working properly (besides slamming on the brakes while driving on wet surface)? When I turn the key to the “ON” position, should the ABS light come on? The battery, Oil pressure, SRS, Parking Brake and Brake Failure come on. Also, the previous owner removed the parking brake all together. The cables are gone; the parking brake parts in the rear wheels are gone too. Is there a parking brake kit I can buy to rebuild it back to the way it is supposed to be? Can someone please recommend a supplier and part numbers?
Transmission: The overdrive on/off button on the gear shifter doesn’t do anything. What needs to be fixed in order for it to work? Should I even bother fixing it? The car shifts smoothly all through 4 gears.
Thank you in advance for all your help.

 

there is a low pressure switch on the reciever/drier, one wire comes from the AC controller in the dashboard... start the car, turn the AC on, and put a volt meter on this, you should see +12V relative to ground on both terminals (as the switch should be closed if there's sufficient refrigerant in the system). if you do see +12V on both sides, the wire continues to a high pressure switch on the coolant manifold on the AC condensor on the radiator, this switch also should be closed, so you should see +12V on both sides.... the signal then goes to the clutch on the AC compressor. if either of these pressure switches is open, you could jumper across them to see if the AC comes on...

also, you could disconnect the control wire from the compressor, and jumper it to +12V and that should activate the compressor, and you'd get cold air if the system was otherwise all in operating condition.

 

1991 240 does come with ABS. If you previous owner removed the parking brake, you might see if the unit is in it... as I really don't quite understand why that would be out in the first place. The ABS unit should be here:

The ABS light ought to come on when you turn the key to position II, but go off after the car starts running. Usually, if the ABS is NOT working, then the light stays on. I'd check fuses (they are often a problem) and verify that the bulb is not burnt out.
As to parking brake, I would just recommend going to a junk yard and try to find the parts on a donor car. But I've got no other leads for that.

 

oh, re' your OD question. the button controls a relay thats under the dash. the relay controls the light and a solenoid on the engine. the light and the solenoid are on opposite poles of the relay (so, if everything is working properly, when the light is ON, the solenoid is OFF, and OD is disabled, the car will stay out of '4th'. if the light is OFF, the solenoid is ON, and OD is enabled, the car will shift through all 4 gears).

I see a couple scenarios here. 1) the system failed, the PO either hacked the solenoid or installed the IPD solenoid replacement plate, and removed the relay. 2) the relay is somehow stuck in the 'normal' position, perhaps the button wiring is bad (and is nearly impossible to repair) or the relay is stuck.

 

ABS was an option on '91 240s. Check under your hood. If it has the square box that zjinqui1k noted in the picture, then your car has the ABS. Otherwise you don't.

My daughter's '91 does not have ABS.

Good luck.

 

Re A/C: You can apply direct power to the compressor to see if it works. The rest, you'll have to go in the dash, I'd start with the ON/OFF switch.

Re brakes: Why would anyone take out the parking brake? Beyond me. Best to go to a junk yard and get everything cheap, otherwise too expensive.

If the tranny shifts well and goes in overdrive (4th gear), I wouldn't mess with it. The button just lock out the OD...