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Old 03-06-2009, 10:07 AM   #1
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Default webasto heater overheating?

Can anyone offer advice please? My webasto heater runs perfectly for approx 20 minutes then the overheat trip triggers & it turns off . After 5 minutes I restart it & it runs another 20 minutes & fails again. It starts first time . I have disconnected the out put pipework to the cabins so there is nothing impeding the airflow. The exhaust & combustion pipes are clear. I have stripped the outer airflow casing & there are no blockages. The fan appears to run at the correct speed & we have good airflow. The fan is not stiff & rotates freely by hand : Still the trip operates after 20 minutes! Logic tells me the trip is over sensitive unless someone knows differently? I am loathe to invest in a new overheat sensor unless this is a common problem. Any help appreciated. It is a 3.2 KW heater
Bernardtravis is offline   Reply With Quote
Old 03-06-2009, 03:42 PM   #2
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See if you can find your model here:

Download the manuals and see if they help.
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Old 03-06-2009, 09:15 PM   #3
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As Ron says, a manual will help. I am not familiar with the Webasto details, but if it uses a snap type limit switch, you don't need to be afraid of buying a new one. They are very, very cheap. Even if it uses a more expensive home furnace type of limit switch, they aren't all that expensive. The snap switches are very prone to failure as they age.

Easy way to check is just to bypass the limit switch, once you find it, and operate the heater. See if it then reaches its proper temp and cycles normally on its thermostat. Obviously, you must stay near the unit at all times while running this test, since if the unit should really happen to be overheating, there is nothing to protect it while the switch is bypassed.

The cutout temp for either switch should be in the manual and usually will be marked on the switch. You can test it electrically for continuity below and above its cutoff point, or you can also test it by heating it (after removing it from the unit) in a pan of water using a thermometer to increase temp to the cutoff point. The snap switches snap audibly when they open up. Obviously, you can't immerse many of the furnace-type switches in water unless they have the long probe off the side, in which case you can.

Last edited by KeyPineSavage; 03-06-2009 at 09:18 PM.
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