Steve-
Am I missing something here. If the coolent goes to the battery pack does it not become recycled through the A/C pump? See my discussion on the other site also.

Mike Maline - Sdctcher
2005 Ford Escape Hybrid Owner
California School Teacher

Perhaps it'll help if I parse the language a bit more precisely. In particular I want to differentiate between "coolant" and "refrigerant" and between "pump" and "compressor".

I think we're talking about two different things...so I'll review the details of what systems cool what components so as to try and standardize our terminology.

1. The ICE is cooled by a conventional water-based cooling system, just like any "normal" car. This coolant loop also has an additional electric water pump (besides the engine-driven mechanical pump) to provide hot water to the passenger cabin heater when the ICE is shut down.

2. The Motor/Electronics coolant loop is also water-based. It has an electric pump, and runs coolant through the electric motor/generators in the transaxle, along with the inverters and the DC/DC converter.

3. The HV Battery is air-cooled. Two fans inside the battery pack circulate air across the cells, and several temperature sensors inside the pack monitor conditions. If the temperature in the battery pack gets too high, the battery pack controller will send a signal to the PCM requesting that the AC compressor be engaged to provide refrigerant (R134a) through the battery pack AC loop. A electrically-operated valve in the AC system can route refrigerant to the battery pack evaporator, the cabin evaporator, or both (apparently the "jump start" charger can also serve to _heat_ the battery pack, but that's another topic entirely).

So, we have a total of 3 coolant pumps (2 in the ICE loop and one in the M/E loop), and one AC compressor.

From the descriptions I've read, the TSB appears to deal with the coolant pump in the M/E loop. This makes sense because if coolant wasn't flowing through the M/E loop the motors and or inverters/DDC would quickly overheat and shut down the system. Incidentally this would light the high-temp idiot light on the dash, which can signal an overheat in either coolant loop.

Hope this helps.

Is statement #3 then the reason that the engine does not always shut down when you stop? Because the AC is on?

O.K. Go very slow. I am but a simple accountant. When my car is in EV - I have no cool air. The air conditioner works find as long as I am not stopped or driving slow enough for EV. However, if waiting in traffic, the air stops being cool. Is this normal? It is especially a concern since I live in Florida and the very hot season is about to start. If normal, then I guess I will have to switch to Max Air during the summer when in traffic. Please let me know what you think

The AC compressor is run off of the ICE... same as any 'regular' car. It's the compressor that chills the air (though it's not necessary to run the fan). So when you're using the AC (not set to Max), then when the ICE shuts down, so will your cold air. AC Max (and defrost) give the AC priority to run full-time and therefore keep the ICE running constantly - and thus reducing fuel efficiency.

Could be, could also be the engine wants to run to charge your battery, or warm the engine/catalyst to optimal operating temperature.

There are many possibilities...but the AC is one of them.

Exactly. However, in very warm conditions, the AC may come on of its own volition to cool the battery, in that case it will also cool the cabin since you've selected the AC to the "on" position.

You are right that without the engine running the AC will become warm that is why in max AC it forces the engine to run continuously.