Hi

When I turn on the ignition there is an intermittent whirring noise coming from a heating/cooling vent. The noise stops after about 10-20 seconds.
The AC works very well but the heating does not work well.
Has anybody had this issue and resolved it
Many Thanks
Adrian

[2005 xj 350 3.6 European model]

 

I do have a sound coming from the fan on pos 1,2,3 after i turn it one higher it is gone.
Under the dash the heater core might be clogged. Did you change your coolant yet ? If not might be worth flushing it backwards ,so the dirt is being rinsed out, before putting new coolant in.

 

Heating, check coolant and thermostat. If 'stat is not opening you will not get heat. Temperature gauge in the dash is not accurate. If you have an OBD II plug it in under the dash and check the coolant temperature. The 4.2L is happy at 210-215F. Noise in upper vents, might be electric motor that fundamentally opens/closes vent operation. Good luck.

 

After further observation it would appear that the whirring sound is coming from under/behind the glove box and not from the vent. Moreover there is practically no heat at all.

Would I be correct to ascertain that I need to replace the matrix core or should I first attempt to reverse flush it?

Thanks

 

Behind the glove box is the fan that pushes air through the heater/aircon unit. If you're getting little heat it is highly likely the heater matrix is clogged. Flushing very rarely works well if at all, and you're better replacing the matrix. This, fortunately, is not a huge job. Don't let any shop fool you that the whole dash has to come out; it doesn't ! What is removed is (1) glove box, then (2) heater fan unit. The end of the matrix is then revealed and can be removed. I had mine done by the local main agent and was not hugely expensive even at their labour rates, because the labour content is not large. On my invoice I was charged for a fittings kit that was almost the same as the matrix ? However all was OK afterwards.

 

Thanks Fraser.
1.Should i also replace the fan as well as the matrix?
2.Can this be done by oneself or by a mechanic?

 

Before changing the matrix ensure that the Bosch auxilliary pump is rotating and pumping.