Cusser, thanks for the response. Very helpful. From your past posts I think my problem is the blower resistor. Compressor only works on speed 1, but no blower. speed 2, no compressor no blower. Speed 3 and 4, blower only. Now to locate the resistor and test. I’m going out today to find, remove and test. Any problems getting the $15 resistor at my local parts store verses OEM?

Thanks again. Got to keep the old gal running.

 

I doubt that there are many manufacturers of this part !!! Mazda buys it from someone. I'd try the $15 one myself, as these are straightforward R&R.

Where did you find one for $15? Link, please.

 

https://shop.advanceautoparts.com/p/...mtx/11034386-P

 

Cusser. Thank you for all the information. Installed resistor and now have air flow with all speeds. Initially I didn’t have any AC, but was able to quickly cycle the blower speed switch off then on and the compressor kicked in. After that blower and AC worked even when turning off the AC and turning it back on. For the last couple of years I had to sometimes do the switch cycle thing to get the compressor to work. That’s the reason I thought the blower switch was causing my recent AC problems. My guess is that the cycling the switch is sort of jump starting my compressor and might be indicating that my compressor is on its last leg. Does this make sense? Where else to look?




Thanks

 

Bailey - do you still have an AC problem like compressor is not engaging, or is everything working?

If the compressor's AC clutch is not engaging, then troubleshooting is required to find out why. First check is to check the static pressure of the refrigerant, as too low prevents the pressure switch from closing and passing voltage. As to the push-in switch, does the little light in it glow dimly when switched on? One can also test the wire to the AC clutch itself to see if that has 12 volts positive when the AC is switched on,

 

If my truck has been sitting for awhile (maybe as short as a couple of hours) and I turn on the AC by the blower switch (with the AC switch pushed in) sometimes the compressor does not engage. If I turn the blower motor switch to off and then turn it back on to any speed the I’ve been able to get the compressor to engage and it cools very well. Pushing the AC switch in and out engages and disengages the compressor correctly. If I restart the truck after a short period the compressor engages correctly as soon as I turn on the blower motor switch with the AC switch pushed in. It acts normal. I suspect that the cycling of the blower motor switch is bumping my compressor. Sort of like double switching a Florescent light fixture that having a starter problem.

I don’t think it’s the AC switch but I can’t see any light coming from the switch bulbs. It cools very well so I’m assuming it’s got the right balance of Freon. Just wondering if my compressor clutch is getting weak and requires a bump when the compressor has been sitting for awhile. Like I say, once it engages it performs normally until it sits awhile.

 

I don't think I'd do anything to this at this point, as you have a workaround.

Some compressors have a spacer shim or two and a shim can be removed to decrease the AC clutch gap as things age/wear. I actually did this to my 1998 Frontier yesterday as I had troubleshot its AC clutch as sometimes not engaging when it was getting voltage (I had rigged up a dash light in parallel to the AC clutch wire). This had two shims, and I removed the thinner one to lessen the "gap". So I still need to test that in actual operation, have only driven it 8 miles since then. But I cannot say for sure if Mazda truck Sanden SD708 compressors are similar.

https://www.google.com/search?source...99.rGJ-WG4YZ1E

 

Cusser, thanks again for all the help. My thoughts exactly on doing nothing now. But I will take this opportunity to research removing the shim from my compressor.

 

Funny, once I was experiencing clutch slippage on the Sanden 708 on my Mazda truck. I had two old compressors of mine, so I first experimented on the one with a bad/noisy AC clutch, got that off. Then I removed the good AC clutch from the other. So I moved on to my truck to swap out clutch or remove a shim to fix it, and when I went to remove the bolt in the center, I found it was loose !!! So all I had to fix it that time was tighten the bolt !!! So that's a good thing to check.

I was able to (engine off) turn on ignition and the AC and fan, and that would engage the compressor so I could loosen or tighten that center bolt. On a non-engaging clutch, one can (carefully) tap that center part with a broom handle and oftentimes that causes the clutch to engage on a worn AC clutch.

There's some information and tech stuff here too http://mazdaminitruckin.com/?fbclid=...9kFHGXpimpBTqE