Help! Overheating caused by Air Conditioning ?

alertdriving · 12-16-2007, 05:53 AM

If this sounds stupid let me know.

I purchased a Prius 2002 in Mid July 2007 with 88,267km on it. I have roughly been doing about 1000km per week. Current Speedo is at 116,435. Averaging about 20+km/ltr

Today I got my first warming light.

It was a really hot day 24-26’C and I had the AC on low for about 5 hours, done around 200km of driving with about 5 full stops for around 5-10minutes before the warning light came on.

I was driving up narrow hilly roads, where if you stop on a hill the car would roll back, on the way back down the <!> Exclamation mark in the triangle came one first I thought my door was some how open, but I looked again It was the red temperature warning light.

I rolled down the hill it beeped about 2 – 3 as I went to the bottom and stopped on the flat surface. Turned it off and did the standard oil, water, coolant, obvious leaks and escaping steam check. The engine bay wasn’t even hot, just warm.

But couldn’t see anything wrong. (When I got home I check to see if the fan belt was slipping but it was also fine)

Left it off for about 10 minutes started the car and it was fine. Left it off for another 30minutes just to cool down, and drove back home and it was normal.

Any ideas what could have caused it?

The more I think about it the more stupid it sounds that the AC is to blame. I'm take it to the dealer tomorrow, to see if they can find anything wrong with it.

"I am pretty sure I didnt have the gear in B mode"

patsparks · 12-16-2007, 06:48 AM

Not the AC because the system is designed to cope wit the AC being on. The radiator may be partly blocked causing over heating. Do you have your grill blocked?

alertdriving · 12-16-2007, 07:09 AM

Nothing blocking the grill.

patsparks · 12-16-2007, 07:38 AM

You may need the cooling system cleaned out or the thermostat is faulty, not unheard of. AC will load the cooling system as the condensor is in front of the radiator but on its own it wont cause overheating, especially not at 26'C, maybe 46'C.

**efusco** · 12-16-2007, 07:39 AM

so many possibilities...
Battery temp, inverter temp, bad gas, MAF sensor, gremlins...who knows.

patsparks · 12-16-2007, 08:30 AM

Well that's true I was only thinking ICE temp but it could be other things. The vent on the right end of the rear seat back isn't blocked is it?

jdenenberg · 12-16-2007, 10:43 AM

Pat,

There have been a small number of reports of failing coolant pumps - There are two:

The ICE loop pump is belt driven as in most cars.
The Inverter loop pump is electric (at least on my 2004).

Either one can be the cause of overheating, but since the AC puts an added load on the inverter, I would first focus on possible Inverter loop problems.

JeffD

alertdriving · 12-18-2007, 06:25 PM

Problem Fixed

It was the Inverter coolant pump.

Got it fix.
Yeah.

12-16-2007, 05:53 AM	#1
alertdriving Junior Member Join Date: Jun 2007 Location: Auckland , New Zealand Posts: 5 My Car: 2002 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Help! Overheating caused by Air Conditioning ? If this sounds stupid let me know. I purchased a Prius 2002 in Mid July 2007 with 88,267km on it. I have roughly been doing about 1000km per week. Current Speedo is at 116,435. Averaging about 20+km/ltr Today I got my first warming light. It was a really hot day 24-26’C and I had the AC on low for about 5 hours, done around 200km of driving with about 5 full stops for around 5-10minutes before the warning light came on. I was driving up narrow hilly roads, where if you stop on a hill the car would roll back, on the way back down the <!> Exclamation mark in the triangle came one first I thought my door was some how open, but I looked again It was the red temperature warning light. I rolled down the hill it beeped about 2 – 3 as I went to the bottom and stopped on the flat surface. Turned it off and did the standard oil, water, coolant, obvious leaks and escaping steam check. The engine bay wasn’t even hot, just warm. But couldn’t see anything wrong. (When I got home I check to see if the fan belt was slipping but it was also fine) Left it off for about 10 minutes started the car and it was fine. Left it off for another 30minutes just to cool down, and drove back home and it was normal. Any ideas what could have caused it? The more I think about it the more stupid it sounds that the AC is to blame. I'm take it to the dealer tomorrow, to see if they can find anything wrong with it. "I am pretty sure I didnt have the gear in B mode" Last edited by alertdriving; 12-16-2007 at 06:20 AM.

12-16-2007, 10:43 AM	#7
jdenenberg Senior Member Join Date: Nov 2005 Location: Trumbull, CT Posts: 331 My Car: 2004 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 8	Pat, There have been a small number of reports of failing coolant pumps - There are two: The ICE loop pump is belt driven as in most cars. The Inverter loop pump is electric (at least on my 2004). Either one can be the cause of overheating, but since the AC puts an added load on the inverter, I would first focus on possible Inverter loop problems. JeffD

12-18-2007, 06:25 PM	#8
alertdriving Junior Member Join Date: Jun 2007 Location: Auckland , New Zealand Posts: 5 My Car: 2002 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Help! Overheating caused by Air Conditioning ? Problem Fixed It was the Inverter coolant pump. Got it fix. Yeah.

12-16-2007, 06:48 AM	#2
patsparks Uneducated bird-brain Aussie Join Date: Jul 2007 Location: Adelaide South Australia Posts: 4,539 My Car: 2004 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 13	Not the AC because the system is designed to cope wit the AC being on. The radiator may be partly blocked causing over heating. Do you have your grill blocked?

12-16-2007, 07:09 AM	#3
alertdriving Junior Member Join Date: Jun 2007 Location: Auckland , New Zealand Posts: 5 My Car: 2002 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Nothing blocking the grill.

12-16-2007, 07:38 AM	#4
patsparks Uneducated bird-brain Aussie Join Date: Jul 2007 Location: Adelaide South Australia Posts: 4,539 My Car: 2004 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 13	You may need the cooling system cleaned out or the thermostat is faulty, not unheard of. AC will load the cooling system as the condensor is in front of the radiator but on its own it wont cause overheating, especially not at 26'C, maybe 46'C.

12-16-2007, 07:39 AM	#5
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 13,365 My Car: 2004 Prius Package: #9 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 23	so many possibilities... Battery temp, inverter temp, bad gas, MAF sensor, gremlins...who knows.

12-16-2007, 08:30 AM	#6
patsparks Uneducated bird-brain Aussie Join Date: Jul 2007 Location: Adelaide South Australia Posts: 4,539 My Car: 2004 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 13	Well that's true I was only thinking ICE temp but it could be other things. The vent on the right end of the rear seat back isn't blocked is it?