Heater, A/C Issues

[jake8687]

I have an 11 SHO with 73k mi. At idle with the Heat set to max it will blow cool air and in the summer the a/c even when set to max will blow warm air. Again this only occurs at idle even though the car is at normal operating temp. When the revs are up whether in drive or in park, the air temp is as it should be. The dealer has been useless in diagnosing. "Cannot recreate condition" Thewater pump was changed at 51k mi. I have bled any air from coolant system as described in shop manual. I suspect the water pump is failing again and the dealer wants no part of it since the water pump is under 2yr warranty and they would have to eat the cost to replace for the 2nd time. The dealer claimed no codes were detected. The max engine coolant temp when running is ~220°. Thanks.

 

[SHOdded]

Coolant level and blend door actuators are usually behind these types of issues. In your case, I add radiator fans to the mix. A part that does age over time due to all the demands placed on it. Coolant level should be at the upper end of the COLD FILL range. Only one fan should come on with climate control completely off. If both fans are on all the time, the fans/fan module has failed.

 

[luigisho]

Yeah you need to check the coolant level. I have a 5.0L coyote motor truck, with a common coolant o ring seal failure, and that was the first symptom. Truck was fully up to operating temp in winter and, at a stop light, the heat would drop to cool air-- only to heat up quickly again while accelerating. Not enough coolant in the system circulating through the heater core at idle.

 

[shaker281]

Yeah you need to check the coolant level. I have a 5.0L coyote motor truck, with a common coolant o ring seal failure, and that was the first symptom. Truck was fully up to operating temp in winter and, at a stop light, the heat would drop to cool air-- only to heat up quickly again while accelerating. Not enough coolant in the system circulating through the heater core at idle.

I've had this with the SHO and was only down a cup or two of coolant.

With the blend door actuators (had two fail), it was the same whether at idle or under load.

"in the summer the a/c even when set to max will blow warm air. Again this only occurs at idle" < this part is baffling.

And makes SHOdded's idea of a fan related problem seem very credible. Or a combination of two problems?

 

[jake8687]

Coolant level and blend door actuators are usually behind these types of issues. In your case, I add radiator fans to the mix. A part that does age over time due to all the demands placed on it. Coolant level should be at the upper end of the COLD FILL range. Only one fan should come on with climate control completely off. If both fans are on all the time, the fans/fan module has failed.

I just added over a quart of coolant to the reservoir. It's 18° out so it's a but of a challenge to check the radiator fans since the coolant temp is peaking at 195°. Fans are not going on yet. Don't think the a/c testvwould work on a cold winter day. Thanks!

 

[jake8687]

I just added over a quart of coolant to the reservoir. It's 18° out so it's a but of a challenge to check the radiator fans since the coolant temp is peaking at 195°. Fans are not going on yet. Don't think the a/c testvwould work on a cold winter day. Thanks!

(bit of a challenge).

 

[jake8687]

Coolant level and blend door actuators are usually behind these types of issues. In your case, I add radiator fans to the mix. A part that does age over time due to all the demands placed on it. Coolant level should be at the upper end of the COLD FILL range. Only one fan should come on with climate control completely off. If both fans are on all the time, the fans/fan module has failed.

Thanks for input. After adding only 1qt to reservoir to top off and re-bleeding the system, the lack of heat at idle issue is resolved.

 

[SHOdded]