Head gasket or something else?
 

The heater on my 2003 4 cylindar, 5 speed camry blows alternating cold and hot air when at an idle. On the road it works fine with no fluctuations. You can also hear the water moving in the heater core and and hoses at a stop too.

The engine temp guage stays at normal, I noticed a leak at the back of the engine last week and had it pressure tested. Pumped it up to 22lbs and it dropped maybe a pound over night.

Is this a blown head gasket?

This engine has a tendency for a few of the head bolts to pull of the head due to thread failure in the block. The result can be leaking coolant.

This site has a long thread on this issue including fixes and costs.

Do you have to replace the head gasket when you do this?

And would it pass a pressure test?

Ok, turns out it was stripped head bolts. Two in the back. Funny how Toyota tells me I need to replace the block. How ever, my mechanic is repairing it using the NS200L Helicoil head bolt repair kit. Have read good reviews on it. Did I mention that I bought this car new, and I have had zero problems with it for 300,000 miles. Plus, it is a five speed manual transmisssion.

Toyota has an improved block design but thought some dealers were repairing the old block.