Is the carpet dry? Does the level of coolant go down in the overflow reservoir? Bubbles in the radiator or overflow tank is an indication of a bad head gasket. The bubbles going away when warming up can be due to expansion of hot surfaces sealing head gasket.
Carpet is dry - no heater coil leak. Coolant was slightly low with old cap but then slowly rose back up toward full in a few minutes after the pressure released - and it was still cold. Giving it a week to see if still tiny bubbles on cold starts.
I just solved this in my Tacoma with maybe a similar system. It was the head exchanger valve on the other side of the firewall.
Is the carpet dry? Does the level of coolant go down in the overflow reservoir? Bubbles in the radiator or overflow tank is an indication of a bad head gasket. The bubbles going away when warming up can be due to expansion of hot surfaces sealing head gasket.
Carpet is dry - no heater coil leak. Coolant was slightly low with old cap but then slowly rose back up toward full in a few minutes after the pressure released - and it was still cold. Giving it a week to see if still tiny bubbles on cold starts.