2007 Toyota Avalon , 86k
From PA where spring lasts 2 months and it is 35º today.
In heat mode there is no HEAT. After about 10 miles of highway driving and the lag for the duct work to come "up to temp" only barely warm air is delivered to R or L sides and to the rear center console vents. Defroster blows only cold air.
In summer in A/C mode all vents deliver REALLY cold air.
ALL blend doors are properly working.
Cannot find any valve or actuator to control hot coolant flow to radiator/heat exchanger in the in dash "heater box" and I doubt that coolant flow circuit is not controlled, i.e., "always on."
Cannot locate any temp sensors for climate control system to sense and modulate temp of delivered air/
*******
What am I missing?
Is there a preferred process to evaluate and if needed clear that clogged radiator/exchanger??
(my older car - 95 Avalon - never had this issue).
THANK YOU!
I'd first try to do a proper flush of the coolant system with special attention to bleeding any air out. It's due anyway, and there's a good chance you have air or clogged up passages in the heater core. Also, make sure your cooling system thermostat is not stuck open - I had that happen on a Camry, and my heat disappeared as a result.
Thank you for your response...
You referenced the "cooling system" thermostat. Under this name, this part seems to have been purposefully excluded from the heater fluid delivery/return lines...unless I am missing something...
The thermostat I'm referring to sits between the engine and the radiator - it stays closed until the engine warms up, then opens so the engine can be cooled. They tend to stick open when they fail, and then the engine never gets fully warm - and the heater doesn't work well.
https://auto.howstuffworks.com/how-does-the-thermostat-in-a-cars-cooling-system-work.htm
As Glen_stet suggested, try replacing the thermostat and replace your coolant. I am attaching a video from the Car Care Nut on how to refill and bleed your coolant system, specific to the 2GR-FE engine... I have done this on two Avalons this year. He points out that this engine's cooling system is notoriously hard to bleed if you don't follow this procedure.
This part seems to have been purposefully excluded from the heater fluid delivery/return lines...unless I am missing something...it is not findable on line or on any of the Toyota parts illustrations.
It should be somewhere on the firewall, with two, medium sized black hoses connected to it.
I am familiar with its appearance & location on my 95 Avalon.. That car has a manual temp adjusting dial. On the 07 the two hoses/tubes are not valved at the fire wall.
Look under the dashboard on the passenger side to see if there is a cable connected to a control valve. If it's not there and not on the firewall it's probably on the driver's side and the entire dashboard and gauges have to be disassembled to get to it.
On the toyota parts pages ( https://www.megazip.net/zapchasti-dlya-avtomobilej/toyota/avalon-38211/gsx30-55548/gsx30l-aeagka-914881?vin=1322676961)
There is no valve in the entire HVAC system to control flow from the engine cooling system to the heater core; this flow is continuous.
The A/C compressor only engages when AC is "on"; this flow IS NOT continuous, however, the flow of coolant is either full on or full off dependent upon whether the A/C is engaged or not.
Cabin Temp can be controlled for R or L through dashboard switches for each.
Both blend doors are fully functional
There is a thermister associated with the cold air exchanger, but none in the cabin or heat exchanger in the heater "air box"
The fan (blower) speed is controlled from a dashboard switch. Cabin air may be delivered from the exterior or recirculated cabin air.
Here are my conclusions...
The source of the air being circulated should not affect the temp of delivered air.
The temperature of the delivered air flow from the system and into the cabin R/L is controlled by the two blend doors.
If cold air is delivered (R and L), the A/C compressor and blend doors are performing as expected.
If there is never hot air (R OR L), then the hot fluid flow is not reaching the heater core.
Please advise what is wrong with these conclusions??
THANK YOU!