ceggleston55

2008 rdx, no heat when I turn on the heater. Only cold air. Thermostat stuck open? How do I get to it?

hues10

I live in Florida. That would be a great problem to have if there was never any heat. Just kidding. I would suggest to google it. It can’t be hidden that much. Probably at a connection with a radiator line.

Chopperpilot

I believe your cable controlled heater control valve is stuck in the closed position.

Matt_ATX

The thermostat is real easy to swap on these cars.

drain coolant from radiator
remove lower radiator hose from thermostat housing
remove 3 10 mm bolts on thermostat housing
install new thermostat housing
reconnect lower radiator hose
refill coolant, burp system, done. (The Gates housing on rockauto has a jiggle valve, so it's a bit easier to burp than some others)

With that said, the blend doors in these things are notoriously bad, so I would consider that the most likely culprit. If the thermostat was bad, you would most likely be running hot or cold and it would show on the gauge.

-Matt

Chopperpilot

I’m with Matt on the blend door/ actuator. It has the old fashion cable connected to heater control valve on the firewall. Pull the left side lower console panel and you’ll see actuator plus the cable. There’s one Phillips screw beneath dashboard, the rest are snapped in . I went through this on my son’s 08 , didn’t replace anything, just lubed actuator while raising and lowering temperature control.

The last time I saw thermostat failure it was stuck open , I believe it’s designed that way nowadays.

Tomtwtwtw

Even if your thermostat was stuck open, the coolant should still get warm enough to heat the air (if not as much). It is probably the blend door not switching over as others have mentioned. Sometimes if the coolant level is low it may also not reach the heater core, but I'm not sure if that is a thing on the RDX or not.

ceggleston55

You're right. Turns out its the bend door actuator, not the thermostat. Are these fairly easy to replace?

Matt_ATX

Do you know which side is bad?

Driver's side is a bit easier... you have to remove the lower cover, then the undercover, disconnect the connector, remove the screws (3 or 4 I think), remove the control motor, replace.

Passenger side you need to remove the glove box, climate control, then the motor...

-Matt

Chopperpilot

This is the driver side that controls the temperature . Mine quit on me over the weekend ! My son’s RDX is on its last leg too, but it’ll move with a little physical persuasion . Ordered 2 aftermarket from Rockauto. Replacement doesn’t seem to hateful at this point, the girlfriend’s side , not so sure .
These are times to appreciate those heated seats for sure !

ceggleston55

Replaced the driver side... no luck. However, When i manually put it in the heat position it blows hot air. Could it be a fuse? I checked the HAC fuse and it looks good. Maybe I should check another fuse?

ceggleston55

Didn't have any grease so it wasn't moving the blend door. Put some dielectric grease in the channel and its working great now!