Strange Fan problem

[jqwang61]

My 99 Voyager (4 Cly.) developed over heating. After replacing the fan relay from a Autosalvage, the fan kicked in initial test idle run (w/ AC on)However, the next day, the engine overheated again, and the fan doesn't come backon again.

[yogi_123rd]

Most fan systems have two circuits (and two relays). The low speed fan circuit should come on when the AC is selected. The high speed fan circuit (engine too hot) comes on when a temperature sensing switch connects from the heat. You can test this circuit by removing the connector to the temperature switch. The PCM will see a problem in the temperature circuit and run the fans all the time as a precaution.

[jqwang61]

Originally Posted by yogi_123rd

Most fan systems have two circuits (and two relays). The low speed fan circuit should come on when the AC is selected. The high speed fan circuit (engine too hot) comes on when a temperature sensing switch connects from the heat. You can test this circuit by removing the connector to the temperature switch. The PCM will see a problem in the temperature circuit and run the fans all the time as a precaution.

Thanks. I checked again and found that the problem was due to the connectors to the relay deformed during my diagnosis. I used 12 gauge wire to short the pins 3 and 4 to see if the fan would kick in by battery. This deformed these pins somewhat and upon heating they must have expanded, causing an open. After fixing them, the fan kicked in again with AC on. A few day observation will tell for sure.

This is the first time I come here and found the website very useful. I see that this is a common problem with Crysler's vans, and the postings here are very helpful. It took me a while to locate the relay though, only after checking Auto-Manual in library. Now I am checking some minor oil leak problem.