No Heat on 1999 Buick Park Avenue ?

No heat problems are common problems faced in many other car models too.

In most of the cases is issue with thermostat.

Thermostat is not a costly part to be replaced.

But if you have already replaced the thermostat,then other possibility is clogged or blocked heater core or faulty heater core.

To confirm this check the heater hoses.There are two heater hoses.One is clamped to the top of radiator and other is clamped to bottom of radiator.

Both the hoses needs to be checked,if one is cold and other is hot,then problem is plugged heater core.

Try flushing heater core and see if that helps,if not then heater core is faulty and needs to be replaced.

This details will help.Thanks.

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For car AC related and Heater related solutions. You can refer the options mentioned below:---

Car AC Blows Warm Air ?

http://technoanswers.blogspot.com/2011/10/car-ac-blows-warm-air.html

How to test AUTO AC pressure?

http://howtobyme.blogspot.com/2011/10/how-to-test-auto-ac-pressure.html

AUTO Air Conditioning Troubleshooting?

http://technoanswers.blogspot.com/2011/10/auto-air-conditioning-troubleshooting.html

AUTO A/C COOLING PROBLEM?

http://technoanswers.blogspot.com/2011/10/auto-ac-cooling-problem.html

Fixing refrigerant leak?

http://howtobyme.blogspot.com/2011/10/how-to-fix-refrigerant-leak.html

How to locate Car AC Refrigerant leak?

http://technoanswers.blogspot.com/2011/10/how-to-locate-car-ac-refrigerant-leak.html

CAR AC INTERMITTENT COOLING?

http://technoanswers.blogspot.com/2011/10/car-ac-intermittent-cooling.html

What causes INTERMITTENT COOLING on Car AC system?

http://technoanswers.blogspot.com/2011/10/what-causes-intermittent-cooling-on-car.html

Car AC making Noise?

http://technoanswers.blogspot.com/2011/10/car-ac-making-noise.html

BAD ODOR ON CAR AIR CONDITIONER?

http://technoanswers.blogspot.com/2011/10/bad-odor-on-car-air-conditioner.html

How to Recharge Car's Air Conditioner

http://repairhelpcenter.blogspot.com/2011/10/how-to-recharge-cars-air-conditioner.html