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When my car is idling for too long, engine temperature starts to climb rapidly. When I start driving again, the temperature goes back down to normal. In addition, the heater blows cold when idling but blows hot when moving. No DTC, no coolant leak (as far as I can tell). Could it be radiator fan issue?

 
Rep Power: 224

Have you checked the coolant level in the radiator and reservoir yet?

 
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Yes, both are normal. I recently had my water pump replaced, and in the process it was checked for any coolant leaks and there were none which is how I came to the conclusion that there are no coolant leaks (also because I can't see any). Coolant levels are normal. The issue has persisted before and after the water pump was replaced so it's not a water pump issue either.

 
Rep Power: 222

Tried jumping the fans?
checked if the temp switch for the fans is working?

 
Rep Power: 367

to be sure of head gasket, do the test in the video in the 1st post of this link.

https://www.civicforums.com/forums/3...reference.html

also, plenty of other stuff that are not gasket listed

 
Rep Power: 0

Jumped the fans by unplugging from temp sensor and jumping with paperclip - left fan turned on but right fan didn't (drivers perspective). So it seems something is wrong with the right fan? I am not too experienced with working on cars so if you have a couple of next troubleshooting steps to see if the fan itself is bad or if its something else that would be appreciated.
Edit: I jumped them, turned car to on (didn't start just electrical) and turned on th AC as well. This is what I did that resulted in only the left fan turning on.

 
Rep Power: 367

one of the fans are linked to the AC, so if it is not running the AC (engine stopped), the fan will not turn on

to jump, pull a wire to the battery (not the ones in the car, any wire) and touch the fan connectors (disconnect the connectors first).
if fan does not spin, the fan itself is fubar. It runs, it is something before the fan