HVAC System - Blower

Oka · Post by **Oka** » 08 Jan 2022, 09:02

In the XC90, I am going to flush the coolant with Volvo coolant and replace with a Volvo thermostat. Sometime in the near future, I'll replace the Coolant Temperature Sensor, since it is hidden by the engine.

1. For the HVAC (blower), it takes a long time to heat up inside the cabin, and still, it will not be really hot in the inside. Hopefully flushing and replacing the TStat would help.
2. The blower knob is always set to the max (which is kinda loud). In my XC70s, I normally leave the knob to half way when our temps are very nippy. For the XC90, with the knob max position, the amount of air is like half way in the XC70. The cabin air filter got replaced last month. What would be hindering the air from gushing inside?

Cheers

chitownV · Post by **chitownV** » 08 Jan 2022, 17:19

Sounds like you already explored perhaps the blower might be the issue. The resistor could also be an issue. Depending on your mileage and usage, might be a good time to replace both.

As far as not getting hot in the cabin, is that an air temp issue or an air flow issue? If it's an air temp issue, the cabin temp sensor can get covered in lint/dust/dirt and it can also get damaged. Some people use a low suction vacuum to clean through the temp sensor screen (too much vacuum can damage the sensor). This issue is shared with the S60 and is well documented in their group.
Dirty sensor:
Temp sensor testing:

Oka · Post by **Oka** » 08 Jan 2022, 18:50

chitownV wrote: ↑08 Jan 2022, 17:19 Sounds like you already explored perhaps the blower might be the issue. The resistor could also be an issue. Depending on your mileage and usage, might be a good time to replace both.

As far as not getting hot in the cabin, is that an air temp issue or an air flow issue? If it's an air temp issue, the cabin temp sensor can get covered in lint/dust/dirt and it can also get damaged. Some people use a low suction vacuum to clean through the temp sensor screen (too much vacuum can damage the sensor). This issue is shared with the S60 and is well documented in their group.
Dirty sensor:
Temp sensor testing:

I will get to this as soon as possible.
Thanks for the information.
Cheers

Oka · Post by **Oka** » 09 Jan 2022, 17:03

chitownV wrote: ↑08 Jan 2022, 17:19 As far as not getting hot in the cabin, is that an air temp issue or an air flow issue?

At least, air flow is an obvious issue. At full blast, the air flows as if I would have it in my 01XC70, one-third way. True it's been nippy cold in Anchorage, Alaska, but not in full blast after the car has been running for a while, parked outside. Usually, the car is remotely started, runs for about ten minutes, then when driving, the blower will be set to the max so as to get some heat.

Cheers