HM 4.8 CDS thermostat issue. Need help! | TruckMount Forums #1 Carpet Cleaning Forums

HM 4.8 CDS thermostat issue. Need help!

brian3180

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Mar 7, 2010
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I was extracting a rug and only using the blower and it was under load. Pump wasn't engaged. At one point I went to the machine to check the Hg and noticed that the thermostat was reading over 235 degrees so I engaged the pump to release the heat then switched pump back off. I was a little concerned and confused but I went back to work. When I was done I went to machine to shut it off I saw that the thermostat was at 0. I engaged pump and normally after about 20 seconds or so the machine gets up to 170 degrees. Thermostat wasn't moving. It only went up to 170 when I engaged the salsa. Shut down machine and van to let it reset and cool down. I tried again and the thermostat wasn't moving with pump engaged. Water was coming hot but I could let it run on my hand like hot water under a faucet. Machine is 1 year old. Thanks for any help.
 

Jim Davisson

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Aug 23, 2016
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Check your coolant hoses to and from the heat exchangers with your hand. Is one hot and one cooler, or both cool or both hot? Follow them under the hood and back to the source. If it's passing through the heat core of the van first and to the heat exchangers second you can have flow issues causing lack of heat. Also check the thermo relief valve plumbed into the recovery tank, is it hot in a couple minutes of normal cleaning?