1986 Mercury Grand Marquis Little Heat

1986 MERCURY MARQUIS
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MESQUITE5555
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My Mercury Grand marquis 1986 has little heat entering the vehicle. The blower flow seems fine. I tried to temporarily clamp the Radiator inlet hose to the Engine for just about 5 minutes and it did not change the heat temperature. What would be the best first thing to check or do?

Thank you
Jan 22, 2007 at 7:06 AM
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MERLIN2021
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  • 17,250 POSTS
first thing is the ant-freeze. Second is themostat. third blocked heater core, go to radiator shop and get it high pressure blown out! Do you have real good a/c? check the blend door for binding or bad servo. How is the radiator temp? Hot on top and cool on bottom is good!
Mar 5, 2007 at 6:35 AM
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MESQUITE5555
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[quote:391e499ef5="merlin2021"]first thing is the ant-freeze. Second is themostat. third blocked heater core, go to radiator shop and get it high pressure blown out! Do you have real good a/c? check the blend door for binding or bad servo. How is the radiator temp? Hot on top and cool on bottom is good![/quote:391e499ef5]

The AC works good. The radiator temp is actually very low. I will take these suggestions you gave into consideration and have a look tonight. Thank you.
Mar 5, 2007 at 6:47 AM
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MERLIN2021
  • ✓Experienced Mechanic
  • 17,250 POSTS
A vote would be good! If upper radiator is cold go with thermostat first the clogged radiator!
Mar 5, 2007 at 7:26 AM

Suggested Repair

Because the upper radiator is cool, check the thermostat first, then coolant condition and a clogged radiator. Also inspect antifreeze, have a blocked heater core pressure-flushed, and check the blend door and servo.

Conversation Summary

The owner of a 1986 Mercury Grand Marquis reports little cabin heat despite normal blower flow. Briefly clamping the radiator inlet hose did not change the temperature. The expert recommends checking antifreeze, the thermostat, and a blocked heater core, plus the blend door or servo, and notes that a hot top and cool bottom on the radiator is normal. The owner says the A/C works well but the radiator temperature is very low, so the expert prioritizes the thermostat and then a clogged radiator.

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