AC relay bypass jump!!!

Adding a few pics after doing some more adjustment to the defrost switch last weekend. I now have it set perfectly. The defrost switch will turn off the compressor when it thinks the evaporator could be icing up (early morning summer driving with low A/C load) but the compressor stays on all the time on long freeway trips in the afternoon heat when I want full cooling and no icing is really possible, even at low fan speeds.

azdave - in your last photos of your previous post, you show an access hole you drilled on top of that defrost/de-icer switch for the adjustment. Did you remove that cover when you drilled that hole or just were careful not to drill too deep (or used a drill press "stop") ?

I don't remember my own de-icer switch having an adjustment available.

I do agree that in Arizona one would really have that switch completing the circuit like 99% of the time, and you would get too cold and shut off the AC if it was really staying engaged too long (I'm not a huge fan of adding some hot air from the heater if it ever got too cold).

On my defrost switch, the plastic cover was flexible and easy to remove. I didn't even have to bend the metal tabs. I drilled the hole in the cover while it was off and then slid it back in place. I guess you could remove the cover and just seal the opening from dust with a piece of good electrical tape too. I would never attempt to drill the access hole while it was on the switch. It is a gas filled chamber that expands and contracts with temperature and you don't want to let out the gas! If I could not remove the cover I might choose to melt a hole with an old soldering iron. At least that way, no chips or sharp drill edges would endanger the switch function.

While I'm at it, here are a few pics in the same area showing the blower motor resistor. Another common B2000 failure point.

Here is a close-up photo of the blower motor resistor in case you are having issues there. When this breaks you usually lose low speed on the heat/cool fan function. With A/C selected, it messes up the power to the A/C compressor so that you get a compressor on with no fan or a fan on with no compressor. Really weird wiring choice by Mazda back then..

"Really weird wiring choice by Mazda back then.. " Other manufacturers have used similar set-up. I've only had to replace this once in the 28 years I've had my 1988 B2200, and I installed a used one I had grabbed from the wrecking yard. See http://www.mazdatrucking.com/forum/showthread.php/12985-Blower-motor-and-blower-resistor-check-out for more information and how to check out these.

While we're talking B-truck AC systems, also see related how-to's:
AC clutch R&R (on-truck, no refrigerant loss) http://www.mazdatrucking.com/forum/showthread.php/13282-Sanden-708-on-truck-AC-clutch-or-clutch-bearing-replacement and this one http://www.mazdatrucking.com/forum/showthread.php/13001-Sanden-708-AC-compressor-clutches-removal-(AC-clutch)

Repairing AC push-in switch (5 of the 6 I pulled from the parts yard were bad as sitting) http://www.mazdatrucking.com/forum/showthread.php/14677-Repairing-AC-Push-in-Dashboard-Switch