Hey everyone. I know this is a common topic that has been talked about in here, but when searching I didn't see the exact same issues that we are having.

So, just recently got this car for pretty cheap to use as a spare and immediately after driving it off from the dealer we got it from the wrench light came on and this is the code we get. It drives fairly well once you get going but the MPG is horrible (under 20), and takeoff power is garbage. The AC would blow just straight hot air if its warm outside, too.

Ill save you the details of the back and forth, but they ended up keeping it for a month and essentially saying 'we have done all we can do' and left it at that. They CLAIM they bled the system, changed the MECs pump, and the converter (though I am leery). This morning I went out when it was only 85 outside, and turned the key on and could feel the MECs pump come on but then after maybe 10-15 seconds it turned off. I turned the key off, then back on and the same thing. I got underneath it and tapped on it with a ratchet then turned key on, and it stayed on. Obviously sounds a lot like the pump itself is bad.

But then while the pump was definitely running, I took it for a ~20 mile drive. I know its not super accurate but I put a thermometer in the AC vent and during the trip it was blowing really well and down to around mid-low 50s. Charge/assist gauge was actually moving when it never did before, take off seemed great, and MPG for this small trip was over 30. Sitting still in the driveway for another 20 minutes the temp got up to around 63 but still decent considering it was around 90 outside now and the vehicle wasn't moving.

Now fast forward to an hour ago, when it is now 102 outside. Turn the key, and I can feel the MECs pump on. Let it run for about 15 minutes and the AC vent temp never got below 96 degrees. A few days ago driving it around 15 miles in this heat the AC never got cold, wrench light was on, and the charge/assist gauge never moves either (but it did move this morning when everything seemed to be working good).

I was leaning towards MECs pump, but it seems that it is on now and still not cooling. Is it possible that it is just old/weak or internals not pumping correctly even if its on? Is there any way for me to tell? Anything else I should do to test?

Thank you for any guidance!!

 

A/C operation is critical for battery cooling.

MECS pump has no bearing on A/C operation unless inverter is overheating and ALL electrical systems are at risk. P0A7C likely means MECS pump has failed. If pump is not running continuously when vehicle is on, pump is in question.

 

So if the pump is having issues while getting hot which is very possible, then it sounds like the AC issue is a separate problem?

 

If the pump is not running continuously when vehicle is on, it needs to be replaced.

 

Yes, I understand that. As of now, I’m not sure if it is or not but will try to test some more.

But regardless, would it have no bearing on the AC blowing hot if it WERE bad?

 

https://electricvehicleforums.com/fo...42/#post275401

 

I don’t understand. You said it has no bearing on AC unless the inverter is overheating, but if the MECs is going bad couldn’t that attribute to the inverter overheating?

 

Heh, its pretty simple. No mec pump pumping = overheating. No A/C = no electric mode either and on the 09 you have 2 A/Cs, one in the front and one in the back.

 

I feel like part of my issue is getting misunderstood or something. The pump IS pumping every time I’ve checked other than the very first time when it cut off after a few seconds of power on.

The AC was blowing COLD every time I’ve tested it (with pump definitely working) until it was into the 100s outside but then it was blowing hot.

I’m leaning towards the pump having issues as it gets hot, but would THAT cause the AC to blow warm as well? Or would the temp outside be causing the AC to not be able to keep up and THAT somehow causes the electronics to overheat?

Also what do you mean by back AC? There are no vents or controls of any sort for anything other than basic front AC on ours. Is there just AC going to the batteries?

 

Yes, there is a/c specifically for the battery. A/C and mecs are 2 separate systems. A/C being in the 60s/70s at the vent would be a/c not keeping up. A/c in the 90s is a/c that's not working. Maybe you've only got enough refrigerant to run the front? You are going to have to troubleshot some more. Turn off the cabin a/c when its hot out and it should come on for the battery. If it starts clicking on/off the you're low on refrigerant for the back.

Ideally you want to check the low/high side pressures and all that jazz.

You can try to bleed the mecs again if you're sure it's running and make sure the right coolant is used.