I have a 2007 Honda Odyssey and it is running hot at idle. I suspect it's the cooling fans. The radiator has 2 fans and I do not know how or when they are suppose to operate. Need steps to take diag.

Over heating the engine is a serious concern. With the hood raised you should hear the motorized fan turn on just behind the radiator as the engine requires additional cooling.. If you look in from the rear of the radiator you should see the fan blades.

This electric powered motor operates on a thermostat and when the engine temperature rises this fan should come on. I'm assuming from your description that when driving and air is flowing through the radiator as the car travels the engine is nor overheating.

Check fan motor thermostat, check fan motor and check wiring.

Wiring Diagrams related to the Honda Civic
http://www.wiringdiagrams21.com/category/automotive/honda-automotive/civic

Motor engine cooling fan only runs as engine temperature requires additional cooling.

It can vary. Most vehicles will run at or above 40 psi on oil pressure, but can function at lower ones. Less than 20 psi would be cause for concern for long term wear issues or oil pump failure.

check to see if the fan comes on if not check fuses if it comes on flush engine and radiator then change the thermastate this should cure the problem

You might check your cooling fan at the radiator; it may not be running. If it's not, track it down (fuse or thermal switch) and fix it!

The most common reason for running hot at idle is the radiator fan is not running or pulling enough air thru the radiator. If you have a fan for the engine and one for the ac, the engine fan may not be working.
The radiator fan should come on when the coolant reaches 220 degrees. The computer sends a signal to the fan relay.

GET IT CHARGED WITH FREON IT DOES OK WHEN YOU DRIVE BECAUSE YOU BUILD PRESSURE IN THE SYSTEM BY MAKING THE COMPRESSOR RUN AT A HIGHER RATE

I don't thing there is a short there is radiator fan switch that control these fan, it works off of heat. There is also a fan relay that control look in fuse box inside the hood for fan relay and make sure its NOT stuck , if it isn't then its the fan switch.This switch may be bad and cause the fan to turn on. Replace radiator fan switch located on water outlet on engine and this should solve your problem. A

Check the cooling fan switch. It appears your auxiliary electric cooling fan isn't going on when at idle. and engine temp increases. While you are driving, air is being rammed thru your radiator as you cruise along, so it isn't overheating, at idle, that isn't happening, and the fan should go on as the temp goes up. When the ac is switched on, the fan is being signaled to operate due to the heavy ac load on the cooling system.

check thermostat might be sticking or radiator may need flushing if it only heats up while idling check your electric fan may not be coming on try turning on the a/c the 2 cooling fans should come on then if they do then i would check the cooling fan switch if they do not come on when the a/c is switch on you may have a bad electric fan motor or wiring to the fan or fan relay