Since last year I've had no heat or A/C in my car. Now that the weather is getting really cold it's a pretty big deal. I've replaced the thermostat and the heater core with no results. I took it to the dealership and they say it's likely my heather box assembly and they want $1700~ to fix it. As the car isn't worth that much to me, I was wanting to try and get it taken care of myself.

Apparently the heater box assembly is deep underneath the center dash. Does anyone have experience with this problem on any year D? Any other possibilities? I've been slowly working my way into more and more difficult repairs on my cars, but the HVAC system is what I have the least knowledge and experience with.

Thanks for any input.

 

Perma,


I'm not a mechanic, nor do I want to send you on a wild goose chase. Just want to add my 2 cents to help. I just posted about my (heater core)H/C. So everything is fresh in my head. It's possible you might have 2 seperate issues.
Is the A/C properly charged w/ no leaks?
Does the Blower work? Do you hear it and feel air coming out?
If so, Is it blowing the same temp. airfrom the ambient/outside air.
Have you checked all associated fuses?
I'm sure the mechanic would have looked at all this.

The below is what I found in my 02" Diamante. Not sure what HVAC designs Mitsubishi has changed in 5 years.

The H/Chousing ispretty basic,It's the dampering system that is attached to all the units where it gets technical. Sitting in the passenger side looking through the dash you have from right to left, the following housings attached to each other. Blower unit attached to theA/C condenser/evaporator unit which is attached to the H/C unit. Most of your duct work branches off your H/C housing. Depending on your control selection on the dash, these units work dependent and independent of each other. On the outside of the units/housings there is several servos that control thedampering sytem inside the housings. Don't know, just wondering if a combination of dampers are stuck, due to a faulty servo, if it would produce an airlock on the hot side where it couldn't push any hot air through. You're calling for heat through the dash control , but with the damper closed shut, you just feel ambient temp. air. Maybe being a 97" the A/C will not hold a charge at all. 2 seperate issue, but it would explain your problem. Well hopefully this helps, or provides you with a little more knowledge of the HVAC in the Diamante.