So, a couple of years ago I changed all my hoses and when I finished the job I had no heat. I've pretty much ruled out the heat pump as I get absolutely no warm air even at highway speeds, and given that the heat was fine before the changes, it's unlikely the pump failed while I was working. I suspect I managed to mix up the valley hoses, although I don't know how I would do that since the hoses are shaped to follow specific paths. My question is whether misconnecting any of the smaller hoses also could lead to no heat? The car runs fine but it's impossible to use on cold days.

Thanks!

 

The hose to the heater core with that one-way valve has that flattened section. Maybe installing it a certain way collapsed that section and there is no flow. The pump is just a spinning magnet, I could see the flow being stopped pretty easily if there is an collapse of that hose section.

Otherwise, the other tests apply:

• Key on, heat on, engine off, you should be able to determine if the pumps actually runs.
• Disconnect the heater valve at the firewall. It defaults open and should give you PLENTY of heat.
• You can use a laser thermometer and gather data as to the temp of the coolant in the various sections. Sometimes carefully touching the hoses tells you plenty.

FWIW, this type of scenario has happened to me before, and I got great results off of a simple heater core cleanup. Forward and back flow through the core, with simple clear tubing and a garden hose adapter from the hardware store. Add radiator cleaner and a 10 min soak for good measure. The design of our cooling system is high-flow, low volume, so you should have _some_ heat coming off the vents within, say, a mile of driving, at least as soon as the temp needle comes off the lower peg.

Best of luck, keep us posted.

 

Thanks for the tips. Apologies for the slow reply. I haven't had time to get back into my heat issue until this week. I'll post my findings. Fingers crossed.