controller seems to be functioning fine, good vacuum...but with contol in heat moad still getting cold air out of center ducts and defrost ducts. defrost pod working....recirc door behind glove box working...what am i missing???

.....telling us what car you are writing about. If you are wanting a guess - I will guess your monovalve.

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DUH.....sorry...1984 300sd federal car. wont get the inside warm.

Do you get any heat at all?

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'83 300D Turrrbo 295K miles

yes.. it would seem that the heat part is ok its just that its letting cold air into the center and defrost ducts. looking in the owners man it shows vent air coming in in the cooling mode but not in heat mode, I wonder if that sensor is screwed??

I need to find out this solution as well.

Currently the SD does the exact same thing. But, I have permanently connected the vacuum to the center vent pod so that I would have driver's control of the center vents via the dash.

Unfortunately, cold air is delivered to the center vents and a small amount of cool air is exiting out of the defrost vents.

So, apparently, we both have vent air coming into the cabin in some fashion. I'm not sure if it's related to my center vent modification........or not.

Well it appears to be the controller. After switching out 3 I had on the shelf, the last one at first glance appears to be functioning. Does anyone know of a way to test these? Is the fix just to resolder everything and hope for the best or is there a definitive function test? Will update after puttind all the ductwork back and test driving.

Could this be my issue also? I have a perfectly functioning monovalve (I double checked this) and I still only get mediocre heat with the fan above a low speed. On low its nuclear hot air drifting (fan speed 1) from the defrost/floor/side vents depending on the setting, but when I increase the fan speed, the air cools off to a "lukewarm to cool" temp. My only guesses are a flap issue, or heater core plugged up? My aux pump has been squealing and begging for death....so I will change that out tomorrow when I replace my thermostat....we'll see if new t-stat (my temps are about 8-10C low right now) and aux pump solve it. If not....what should I look at next?

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possibly...have you checked the aux pump??

Brian... took four ccu's but found one that seems to make everything work. Its actually toasty in the car now while driving.

Fixing that Damn Climate Control!
http://207.210.95.34/~boostd/Climate/

DIY page. Introduction to Resoldering Climate Control Unit
http://www.peachparts.com/shopforum/diesel-discussion/86958-diy-page-introduction-resoldering-climate-control-unit.html#post567735






Have a great day.

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1985 300SD
1983 300D
2003 Volvo V70

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I really wish I understood why the CCU is allowing cold air out the defrost vents. I wonder if it's getting a portion of the air that's directed to the center vents. I've got to replumb the pod and see if that cures the issue.

Otherwise, it's probably a CCU for the SD as well.