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Heater core clogged

I have a clog in my heater core in my 1993 Pontiac Grand Am and I need to figure out how to get rid of the clog? Right now I have no heat and I would like to get that fixed before winter totally gets here.

If you have a heater core clogged in a 1993 car, it is best to replace the core. However, make sure it is the heater core, and not a stuck circulation valve, which some older cars have.

One thing to try before replacing a heater core is, disconnect the hoses from the heater core and attach short hoses. To these short hoses attach plastic elbows that point up. To these elbows attach two foot long hoses. Now take a product like Lime-Away or CLR and fill the hoses. Let this product sit in the heater core for a couple of hours and then flush the heater core. Sometimes this cleans out the heater core so that it functions again. And if the heater core leaks after doing this, it doesn’t matter. You would have had to replace the heater core anyway.


Disconnect BOTH heater hoses from the ENGINE and try to reverse flush it with a garden hose. This will give you some idea if it’s really clogged and if so, how badly it’s clogged. Many times, the problem is the “blend door” in the heater/AC unit located behind the dash. Sometimes you can access that by removing the glove box.

If the core is truly clogged, I have had some success boiling them out with Muriatic Acid, (used to clean masonry). But be warned, this is a tricky and hazardous process and must be done VERY carefully.

check the valve.coolant level?

good luck

Some brand new cars have these valves too.

how has the AC been working on this car last summer?

has it been acting funny, getting cold, then getting hot for no reason?

now that you need heat, is the fan blowing? on all speeds? is the heat EVER on? maybe goes cool or cold?

have you checked the radiator temperature? is the radiator getting up to correct temperature? a broken thermostat will mimic this cold heat scenario too.