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Posted by: David Devoted on 2010-07-23, 12:56:23
Things to check: 1. Does your auxiliary electric fan cycle on/ off with the AC or Defrost on? (it should) 2. Can you force the aux. fan to come on by unplugging it's harness and then running two temporary wires to the battery? 3. After they changed the water pump, did they make sure to purge all the air out of the system? (google "purging air out of cooling system). Mainly, open the radiator when cold, leave the cap off, start the engine, put the defrost on hot, and then squeeze the radiator hoses a bunch of times to make sure they don't have air in them. Let it run until it's at full operating temperature to make sure the thermostat opens, and then keep filling it slowly with water/ antifreeze as needed. Also make sure the overflow bottle has water/ antifreeze in it too, because when an engine that is low on coolant cools down, it will suck coolant back in as it cools off. 4. Make sure the shop didn't make your mixture more than 50/ 50 with water and antifreeze. A Cherokee's capacity isn't very large, so it's easy to put in too much antifreeze if you don't pre-mix 50/ 50. Antifreeze does not cool as well as water because it doesn't transfer energy as well. If it's heating up going highway speeds, then it's not the electric fan or the mechanical fan clutch. If it's only heating up at slower in-town speeds or at idle, it's possible it's the aux. fan not coming on or the mechanical fan clutch is bad. |
