Hey guys, searched and only found one thread.

My heater is really weak. With it getting steadily colder it's been painfully noticeable. I know the blower works awesome. I had it out in the summer while I was going over the A/C and tested it out of the housing with the stock controls. I had been contemplating pulling the dash and going over all the ducts, heater core, etc. but that's not really an option with my work schedule. Also have been thinking about running hoses to the inlet/outlet on the heater core and running that Prestone flush through it with a small pump overnight, but I've heard that can cause problems, unplug hidden pinholes, etc. Looking for some input on things to check, maybe someone else has had this happen.

I'm sure it's not likely, <strike>but you probably can't access the core without pulling the dash, correct?</strike>
Nevermind, found the answer. Will probably do that if a flush isn't the best route.

Car is an S4 N/A.

 

Easy check:

(use pdf page 38)

http://www.rotaryheads.com/PDF/2nd_g...AC_systems.pdf

I know it's the S5 manual, but it should work the exact same. I couldn't find the HVAC portion for the S4.

 

The car gets up to temp bit no heat?

 

Well, I've been having a separate problem with that. At highway speeds it stays right around 170. At idle it will hold 195 all day but still doesn't get very hot.

It's pretty much the same temp coming out of the vents either way. I don't have a gauge to check the temp coming out or I would.

 

My car runs cooler than yours and still puts out plenty of heat, so I don't think that's your problem.

I'd pull the dash and check the water control valve, make sure it's actually opening all the way.
Also check the sealing on the flapper doors and clean the ducts while you're in there.

I've heard a lot of folks bitch about the RX heater but I think it's actually quite good.

 

with the car at operating temp, heater on blast, feel the temp of the inlet and outlet core hoses. they should be roughly the same temp. if not, either the core is plugged, or the heater control valve isn't opening.
back flushing is a last ditch effort before pulling the dash. it's easy enough to do and it might help. just make sure you flush in the reverse of coolant flow

 

^^ your heater control valve is probably stuck. The valve is up under the dash on the driver side and has a metal "L" shape control or bracket attached to it. That "L" shape is connected to the actuator rods that when you move your logicon controls, it moves the rods. The actuators commonly stick in a 2nd gen. I just popped the rod off and move the actuator by hand for the season. One way shuts the warm air off, the other way allows warm air in. Not a permanent Fix but easy enough to keep you warm.

 

Unfortunately, when the motor gets stuck. The controls in the logicon burn out trying to overpower the stuck actuator. Often requiring both to be replaced.

I never realized how infrequently I changed temperature until I used the system in 'manual mode'.

 

its also possible the heater is just clogged with crap, i've found flushing it backwards with a garden hose really helps a bunch