Hi my 92 integra with a b20 keeps heating up some.
When I have the heater on and its blowing hot air then randomly the air will blow cold and my temp gauge will go up.
Then it will start going down once the heat starts blowing hot again
Does this sound like a bad thermostat?

Thanks

 

More likely you've got low coolant. How's the coolant level in the rad? Is it right up the bottom of the rad cap when the engine is cold?

 

When your car is warm feel the upper and lower rad hoses to see if they are both warm or just one or the other. Could signify that it is not opening properly which can cause overheating.

Are you sure the cooling system is properly full and bled?

 

Funny i've had this exact same problem. Air wouldn't get warm until the thermostat fully opened and even then if i pulled up to a stoplight it would start to blow cold air again. Literally just checked my coolant...it was low. Problem solved. If that isn't it i'd say your t-stat is starting to go.

 

it def sounds like your thermostat is going, when they start to **** out they will start to cycle and when it is on full open u are getting hot air which is being drawn away from your motor cooling it off, may have low coolant and your t stat is starting to go neways let me know

 

http://www.lmgtfy.com/?q=sign+of+bad+thermostat