I heard mine yesterday, its really no big deal if it is as quiet as mine. I is the A/C clutch engaging when the engine starts, there is about 1/2 second delay in the a/c engagement that is programed into the pcm. It would have been nice if they had programed the a/c to engage before the ICE starts, but this is the way they have always done it. It has something to do with idle stabilization on a normal engine.

 

Yup, that's the chirp, same one.

Summer time the A/C cycles whether or not it's on in the cabin. Evidently to control temps for the HV battery..? Then I've counted the chirps as frequently as 30 seconds apart for several minutes. Good to hear it' not a major issue. Annoying though!

 

Have you had the freon checked? once the a/c comes on it should not cycle on and off unless its low or the rear evaporator is getting to cold.

 

No... 30 seconds on, 30 seconds off, or even 20 seconds on, 20 seconds off is very typical actually if you have the A/C on anything less than maximum fan speed. At Fan Blower speed 4 it is on for 90-120 seconds, then off for 15 seconds, repeat. I montitor mine closely, as I have had trouble with it... plus, I like to know when the HV battery is running the A/C "without my permission" so to speak.

-John

 

John do you get a compressor on/ off on your SGII with the front a/c off? Mine does not seem to cycle with the front on with anything less than blower 2. Of course I live in Texas so ambient air temp is a little higher. If so this is kinda good to know, as I'm thinking about building a device to cycle the a/c when the front was on but was concerned that the rear may not get cool enough but this means the rear does not need much freon to cool the HV battery.

 

I'm not sure what you are trying to manually control and why?

I put in a 12v red LED on my dashboard that lights whenever the A/C compressor clutch is on. That RED led goes on and off very frequently, so that's how I know when the battery is requesting cooling even when I have the cabin A/C set to off.

The red lamp is never "just on" for more than 30 seconds or so at a time.
So #1 the compressor cycles MUCH MUCH MORE than most people realize, and #2 the compressor clutch must therefore be much much more durable than most people realize as well.

While there is one compressor, there are two cooling zones and a computer controlled zone valve. There are two evaporators, one for the cabin, and one for the battery compartment.

The battery cells in the 330v battery are not very efficient.
The have lots of internal resistance ( Ohms ) and create lots of heat.
My HV battery has turned on the A/C on 50'F days.

 

A cycling clutch (in warm weather) is an indication of a low system. Has yours always cycled this much? The compressor on the FEH is just the standard Ford a/c compressor, allot of cycling and it will wear out the a/c clutch. The system is designed to shut off the compressor when the low side pressure drops below 29 psi or the evaporator gets to close to freezing. On a warm day the low side should almost always be 32 psi or more unless the blower is at very low speed and the a/c has been running a while. Your FEH is a 2005 and if you have not added freon or serviced the a/c I'll bet its low, its not uncommon for the systems to loose a little freon over time. However I don't have experience at altitude you reside. But if you set it to max a/c with the blower on high, if its above 90 deg it should not cycle, unless its low.

 

Yes, it always cycles that often, and yes, it has been recently serviced by a Ford dealer and the system has been recharged, and it gets very very cold, very very fast.

I think you have your theory reversed.
I knew my freon was low when the compressor went on and would never shut off ( and didn't get very cold). I noticed it was always running, and took it in, and my Ford dealer said there were bad 0-rings in the refridgerant lines, and replaced the o-rings, and recharged my system with "freon".

Works great now, and cycles every 20-30 seconds.
Cold enough at the vents to be a meat locker.
-John

 

I know the FEH has an evaporator temp sensor maybe they are using this as the primary cycle input, but this would be contrary to all of Ford's other systems. I'll check my Hybrid manuals to verify the operation. But what I want to do is cycle the compressor to control the duct temp without having to blend heated air, mainly on the highway.