Car blows heat in summer, not in winter. Car overheats in winter, not in summer.

Asked by Apr 27, 2016 at 07:37 PM about the 2005 Pontiac Grand Am SE

Question type: Maintenance & Repair

I have a V6 05 Grand Am that has a very strange problem. I cant seem to
get an answer from anyone. In the winter my car will overheat, but then
drop back down to mid level. When its blowing heat its staying around mid
level on temp gauge, when its blowing cold it heats up to the point that
sometimes it overheats. In the summer, the car heats to mid fast and
sometimes goes a hair over mid but never overheats. It also blows heat like
crazy. This winter I had a coolant explosion (coolant everywhere) and the
shop replaced the water pump. I have replaced the thermostat as well. Any
idea's what this could be as even with the new water pump I am getting the
same results.

1 Answer

104,375

I am suspicious of a head gasket problem, when a head gasket blows it starts using coolant, when the coolant get low enough the heat stops working. I would have a shop perform a block check test to confirm a head gasket.

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