11/15/2024
"ATTENTION" Service Masters Vehicle Drivers
It came to my attention last week that one of your fleet vehicle's heater air was not hot.
To the driver, this might seem to be an inconvenience but for me it is a large
"RED FLAG"
warning!!!
The most likely cause for a vehicle's heater blowing cold air is, a low coolant level.
That was the cause for your vehicle.
There was not enough coolant in the system to circulate through the heater core.
MY CONCERNS
1) When a vehicle is being driven with a low coolant level, the engines water pump can suffer damage.
The pumps impeller should be fully submerged in liquid. When the system is low, the pump mixes air with the coolant. That is called cavitation.
It damages the impeller and impeller shaft bearing due to the larger vibration.
2) DO NOT trust the engine coolant temperature gauge when the cooling system is low.
The Coolant Sensor is designed to sense COOLANT temperature. If there is no coolant circulating past the sensor, the gauge reading is inaccurate.
3) When the heater is not blowing hot air, my greatest concern is the possibility of engine failure. Overheating can and will damage the engine.
4) The transmission oil cooler may be inside the radiator. When the engine overheats, so does the transmission.
Please check the coolant level in the morning when the cooling system is cool.
You should see a "Cold" & "Warm" level mark.
Every morning the coolant level should be at the "Cool" mark.
After the engine is fully warm and driven, the coolant level should be near the "Hot" mark.
IMPORTANT!!!!!
In the morning, if the coolant level has NOT RETURNED to the "COOL" mark, there is likely a coolant leak.
The Coolant Recover Reservoir can be completely FULL and the radiator EMPTY.
5) TIP
If the Coolant Temperature Gauge Indicator Needle is not ROCK SOLID, it's varying, that is an indication of air pockets passing by the Coolant Sensor.
Check the coolant level and top off.
6) Tip
There are many types of coolant.
For simplicity, use only Distilled Water.
Do not use tap water.
I don't want Fluorine, chlorine or iorn in the cooling system. It's just chemistry.
Warren Parr
2X's NAPA/ASE California Technician of the Year.
Varying
