I am losing coolant only, in both my CRV and Accord, when only running the defrost. If I run heat and defrost no coolant leak. Checked everywhere for signs of leaks and nothing. But its coming out from somewhere. No coolant leak inside and none I can find outside.

Ideas???

 

I guess one of two things are possible, you have a pin hole leak somewhere....or when your coolant was filled your heater control valve wasn't opened not allowing coolant to get into the heater core...then when you opened it up and coolant started flowing through/got trapt you are now low on the green stuff

 

Actually I was low on coolant. So I filled it with Honda HG AF and it has stayed at the same level. I just had the system flushed maybe they made an error. I just thought it was weird that it was only when the defrost was on.