To: dakota@csclub0.cs.fredonia.edu@INTERNET; ngleng@nbnet.nb.ca@INTERNET
From: Clement_D on Wed, Sep 11, 1996 1:59 PM
Subject: RE: No heat
From: ngleng@nbnet.nb.ca@INTERNET on Wed, Sep 11, 1996 9:03 AM
>I have a 94 Two-Tone Blue SLT, V6, 4WD, Extended Cab with 40k miles. It
has >been a great truck except for one thing: it does not throw heat. It
has been >to the dealer several times to replace the thermostat and check
for >obstructions in the vents. The temperature gauge hand barely moves off
the C. >The dealer says the vent air temperature meets spec, yet it barely
clears the >windows in winter. Believe it or not my VW diesel heats up
better. Does anyone >know how to cure my problem? I think my choices are a
hotter thermostat or a >grill cover. Any help would be appreciated.
Mark,
I think the first thing I would do is get a meat or candy thermometer from
the kitchen and stick it in the radiator to see what temperature you are
actually getting out of the engine.
If the gauge is not moving into the normal range and you do not get any heat
I would expect that the thermostat (I have purchased new ones that do not
function properly from the get go so the fact that the dealer changed it
does not mean that it is not bad) is stuck open or is opening to soon before
worring about a hotter thermostat or blocked vents.
You will need to wait for the thermostat to open up (a 195 thermostat should
start to open around 187 make a few degrees allowance for the distance to
the thermometer) before making any conclusions. Here are some things to look
for;
- If you see water circulating when the engine is cold then the thermostat
is stuck open.
- If water starts circulating and the water temperature does not very
quickly get close to 190 then the thermostat is opening to soon.
- if the water temperature starts cycling up to the 190 range then drops way
down then comes back up but never settles into a reasonably constant
temperature in the 190s then the fan clutch may not be releasing. Block the
air flow throught the radiator with a piece of card board. The temperature
should settle out in the 190's and maybe climb slowly there after. If it
does shut the engine off and fan should turn fairly easily and should get
stiffer as it cools off. If it is as hard to turn when the engine is hot as
cold then the fan clutch is not working properly.
-If the water temperature gets up to the 190's and stablizes and the gauge
stays on the C short the gauge wire to ground. The gauge should go full
scale. If it does then the gauge is ok and the sensor is bad otherwise the
gauge itself is bad.
- Also check to see if when the temperature selector lever is moved from hot
to cold and vice/versa that the the heater core bypass operates (its near
the break master cylinder on my 89 in the heater hoses). Note: vacumn
operates this valve so the engine needs to be running. When the valve is
open the hoses should feel about the same temperature on both sides of the
valve.
Good Luck!!
Dave Clement
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