HVAC Malfunction??

[north42g]

Hey Guys -N- Gals,
Merry Christmas! Happy New year!

My Mazda Protege5 [100400 original miles]
is having HVAC difficulty.
I am looking for correct Factory information;
My A/C Compressor is cycling whenever I call for heat; not defrost, just regular heat.
Should the A/C Compressor be cycling when just heat is called for? Something tells me it shouldn't be coming on/off all winter long?!... right?

So what should it be doing?

I think I read some where that the A/C should cycle on only when called for and when the defrost is selected. Is this correct?
What could be going on here?

 

[sleepwalker]

Typically when defrost is selected, the A/C compressor cycles on by default. This is because in addition to cooling the air, it also dries lots of humidity out of it - great for getting fog off your windows.

When I owned a Neon, the A/C would cycle on only when defrost was selected (even if it was the defrost/floor combination) but once the switch was fully on Floor, the A/C would kick off again.

One of the first things I noticed about my P5 was that even when full-on Floor is selected, the A/C still cycles on. I have to turn it at least to Floor/Vent to make it stop.

It kind of annoys me, honestly - I hate it when they make my car think too much for me. In the Neon, there was a quick and easy mod to fix it to where the A/C would ONLY cycle on if the A/C side of the fan selector switch was used - it involved removing the entire HVAC panel and drilling part of the plastic out to sever an electrical path. I don't know if that can be done with the P5 system, I've never had the HVAC panel out - something I need to do anyway, to fix the A/C-flickers-on-fan-2-and-3 problem AND replace the blower motor resistor - my fan only works on 4.

 

[Rickeroo]

This stupid design defect has been in place since Gen3 1999-2003.5 and was not been corrected until the 2010 Mazda3. This correction just about coincides with Ford selling most, if not all, of its' stake in Mazda. Not saying it is related but....

Back in 2003 a member figured out a clever fix that involved cutting a connection on a main circuit board behind the center CD player. I no longer have a copy but maybe it is in some archive, or try to email him at zapwizard.com to see if he still has the fix to send to you. The guy really is a wizard. If you get a copy try to have it placed in somewhere around here so others can access it.

 

[north42g]

Thanks; I'll try to contact him/her for the info. Mean while I am going to try and find the Factory Service Manual's version of how the entire HVAC system is designed to operate.
Thanks.

 

[Rickeroo]

I found it !
Look at the "All Mazda Tech" forum in the "How To" section for "Disabling automatic AC-Defrost" .

 

[north42g]

That's a good idea. I bet it works very well. However, in my world...the A/C cycles on during every vent position.
There must be a problem somewhere. Before i resort to modifications, I want it restored to factory. Know what i mean?
I just want it to first work the way it was intended. Thanks for the info...it is a good idea.