AC relay bypass jump!!!

Hello fellow B lovers. First time owner. I have a 91 RCSB of course 2.2L Carb w/ M5 tranny. So ive figured that it's my relay in glovebox that's gone bad. Well I believe its the main ac button with the light. I've jumped the relay and the compressor turns on blows cold etc. Just haven't had it on long enough to see if it cycles on and off yet. Said by that to say this, if I keep it jumped will it cycle safely til I get the problem fixed?? Also, if doing that will I blow stuff up?

You really need to put a set of gauges on the system to make sure that the system has enough Freon in it to be pressurized properly. Bypassing the relay may burn up your compressor.

Much appreciated. Where could I get one of those ac button harnesses so I could plug a new relay switch?

Bypassing the relay or pressure switch should be done for just a second or two to demonstrate that the AC clutch engages and that the compressor turns, or you could do damage if the system is low on refrigerant; the refrigerant moves the refrigeration oil.

From what you have written the system has some charge in it already?
Agreed, put gauges on it. Attach the gauges hoses to the compressor fittings and, with the gauges closed, loosen the hoses slightly at the gauges for a few seconds. Tighten the hoses, open the high side gauge (this will blow Freon out the can attachment hose. flushing air out of lines), close the high side port. Attach a can of oil charge, invert it, open the high side (small line going to the condenser in front of the radiator). No worry, if any excess oil, it will accumulate in the big odd thing on the passenger fender well before the a/c line goes in the firewall..
Start the engine, set the engine at a fast idle (1500 r.p.m. in some way) turn on the a/c and temp down. and see if it will engage with the pressure sensor switch hooked up, if so check pressures of gauges. If the low side drops below zero, open the low side port, BUT WITH THE OIL CHARGE CAN NOT INVERTED. If the low side still drops below zero, close the low side port, replace the can of oil with a can of Freon (NOT INVERTED) and open the port charge on the low side ( the large pipe port).. As the temperture of the can drops, from the evaporation of the freon, you may have to put the can into a pan of hot water, to raise the pressure in the can.
In the event the compressor does not start when you engage the a/c, then you will need to bypass the pressure switch below and in front of the battery to charge. Reconnect this as soon as possible, costly later if you forget to, trust me.
Normal way to tell the charge is right, when low side is staying above zero with the low port open and Freon can not empty, Wrap your hand around the (low pressure side) big line coming to the back of the compressor. When you feel a cold surge through the line, close the low side port, disconnect gauges, replace port caps, enjoy the snow on a humid day.

Hey if I missed something here, please jump in and inform me/us, I have been away from auto repair as an income for decades.

Bypassing only the main A/C power relay does no long-term harm but bypassing any low/high pressure cut-off switch should only be done for brief testing and you really should have gauges in place to confirm that. I've had issues with the defrost switch inside the evaporator getting out of calibration. On my 87 B2000 I was able to remove the glove box and then access the fine adjustment on the bulb-type defrost switch so it no longer turned off the compressor way too early. If this switch is out of adjustment you'll either get reduced cooling (if the switch is opening too early) or the evaporator will ice over and eventually block the air flow (if the switch is not opening at around 30-32 F.)

In this picture, the evaporator box lower cover is removed but you don't have to do that to access the switch adjustment on top of where the wires connect. This lower cover was removed for cleaning the evaporator. Hint, removing the cover is NOT easy. 3-4 spring clips on the back side are really tough to access.

Yes, removing the lower evaporator cover is a distinct challenge. Use a small screwdriver and eye protection to remove those little spring clips. If you disconnect the two end "band" clamps first, there's a little more wiggle room to get to the clips on the "hidden" (front) side.

I've had my lower cover off 3 times in the last month to check for leaks with UV light or oily residue while trying to see if I had a refrigerant leak.

I'll also say that I did rig up a dashboard indicator light parallel to the AC compressor which lights whenever the compressor is getting voltage. Here in Arizona, the temperature has to be like under 85F in general outside for the AC compressor to actually cycle off.

Hey Cusser...did you notice I re-used your photo? It came in handy when I was tearing into my evaporator to clear out the crud. Thanks!

Yes, It was 108 here recently and my A/C was cycling on and off way too early due to the defrost switch setting. While working on the system I added several simple LED status indicators so that I could see if the pressure switches or temperature switches were shutting off the compressor.Once I knew it was the defrost switch opening up the circuit, I found that the white plastic top cover could be slid open and that the switch has an adjustment dial. (CCW = colder).

Over 10 years ago I changed over all my A/C vehicles with the old R12 to run propane (ES12a or similar) instead. I currently have 4 cars and truck using these hydrocarbon refrigerants and love it. Way better than R134 and of course R12 used to be stupid expensive (and still is not that cheap). I do all my own A/C work so I don't have to worry about local mechanics that are required to follow laws and shop protocals. Some people freak about using propane but with only 9 oz in the system I'm way more worried about 16 gallons of gasoline underneath.

If that was my photo, then someone else added the graphics/text.

Found it.

It was axle breaker earl's picture from this thread.
http://www.mazdabscene.com/threads/24188

I cropped and added the text to better show where the defrost switch was located.