2000 Civic Si (Canadian) SOHC 1.6L. I recently replaced all the components of my AC because I just bought the car and it wasn't working. Car blows nice and cold now. I'm like 70 percent sure it blew hot air before but I'm now second guessing myself as I dont get hot air at all anymore. Blower fan turns on and works at all speeds but I do get a weird high pitch noise from it every now and again and I want to say the speed changes sometimes as well. I assume thats just the bearings or something.. Every hose that has coolant running to it, is hot to the touch when at operating. Coolant level is good to go. I have a new Thermostat that I was going to install but I'm not having any engine temperature problems so I'm a bit hesitant to change it for nothing. I'm really wanting to try everything before tackling a heater core. Hoping someone has some insight on this. One thing I did find was that the line that comes from inside that opens and closes a valve when turning from hot to cold, was disconnected. I reattached it and this is also doing this, some time later I noticed I do get hot air. I went out and tried disconnecting that line and operating the valve by hand but no such luck getting heat. I was also getting hot collant on the other side of that valve, which tells me it must be opening like it should when heat is selected right?

 

if both hoses are hot, then bypass the valve at the firewall. Also, flush the heater core with the garden hose.

 

Bypass the valve? How exactly do you mean? Clearly something is going over my head here haha.

 

take the valve out of the system. remove the valve and connect the hose directly to the heater core

 

Ok thats what I thought you meant but Ill have to get an adapter to connect the hoses to each other because they will be soo short without the valve

 

Or just get a new valve.

 

What would getting a new valve accomplish? Both hoses on either side of the valve are hot. That tells me fluid is getting passed the valve, meaning it is, at the very least, stuck open. But, when AC is selected, the valve turns and i get cold air, which means the valve must be closing. Am I thinking this incorrectly?