Today, we had a Viper alarm system installed in our 03 Civic LX. On the way to the shop, I had the heat on and it worked fine - it actually gets so hot that I have to turn it down. After they installed the alarm and we picked it up, the heat never got even warm. It felt like we had the air conditioner on. We drove for about 20 minutes, so the car should have reached operating temperature. The temperature gauge on the dash read almost at 1/2.

We searched on the forums and checked the obvious trouble sources - coolant levels and fuses, both of which are fine. After checking those items, we checked the car again...we let it idle for about 15 minutes, still no warm air. It's blowing, but it's blowing cold air.

Now....started to look around to see where any alarm wires were run. We noticed that the power wire for the siren was placed through an existing hole in the firewall. It's a blue tube...it looks like there's a cable that runs through it. They had to dislodge the rubber grommet it travels through to place the power wire through the firewall. Is this blue sheathed cable the heater valve cable? Could they have moved it around enough to disturb the heater valve's operation? Anyone got any other suggestions of where to start looking if this is not the heater valve cable?

Thanks for any help.....

 

Here's how to check the cable:

 

Is the housing for this heater valve cable blue?? I need to know if I have identified the correct cable....and if it's grommet is dislodged from the firewall, will it affect it's ability to control the valve within the engine bay? Thanks.

 

I don't know the color of the cable. It's the cable attached to the heater hose valve on the firewall. Move the heater dial on the dash from full to no heat and then from no heat to full heat. The valve should move. If not, it may be disconnected under the dash.

 

If my assumption is correct and we are speaking about the same cable, I get approximately a half an inch of movement under the dash and only about an eighth of an inch of movement at the firewall. Again, the grommet that holds the cable's sheath is disconnected from the firewall. Could this be affecting the travel of the cable inside the sheath? If I manually push the lever by the firewall towards the passenger side, we begin to get heat. Then, I go in the car and adjust it to cold and then back to hot again, there is no heat. So then I push the lever by the firewall toward the passenger side and we get heat. I'm trying to determine if my assumption is correct and that the grommet being moved has affected the cable's ability to push the lever to the heat selection in the engine compartment.

I can't physically get my hands on the lever inside the engine bay, so I'm having to push it with a plastic tube.....so I'm not sure how I would be able to get my hands on it to disconnect and reconnect it.