Air con ticking noise

BigTom · Post by **BigTom** » Fri Apr 19, 2013 8:30 pm

Hi all,

Recently the air con has started making quite a loud ticking/clicking noise from somewhere on the passenger side. Thought it might be the blower fan but ruled that out as the noise remains even with the blower unplugged. What should I check next?

Cheers,
Tom

The "S" express · Post by **honda-hardy** » Fri Apr 19, 2013 8:32 pm

is the noise coming from the cabin or under the bonnet? if under the bonnet, it could be the clutch mechanism on the pump.

BigTom · Post by **BigTom** » Fri Apr 19, 2013 8:33 pm

I think the cabin, but need to check properly. Sounds like its behind the glove box at any rate.

The "S" express · Post by **honda-hardy** » Fri Apr 19, 2013 8:37 pm

best to drop the glove box and investigate further. 2 screws and the box comes out. it could be the evaporator expanding and contracting due to temp change, the frame the evap is in could have cracked allowing for more expansion.

BigTom · Post by **BigTom** » Fri Apr 19, 2013 9:01 pm

Will have a look tomorrow. It's a very rapid and consistent noise (like something stuck in a fan) which comes on and off almost instantly when you press the button, rather than something creaking as it expands.

A bit intermittent as well, but present more often than not.

The "S" express · Post by **honda-hardy** » Fri Apr 19, 2013 9:10 pm

i have just looked in the manual. it could be the mode control motor. this is the motor that moves the flap to make the direction of the air change, ie floor windscreen etc. does it select each position when you press the button?

BigTom · Post by **BigTom** » Fri Apr 19, 2013 10:35 pm

Yeah all blower modes work fine. Just as soon as you switch the AC on it starts ticking. Is there another fan which only comes on for the AC?

Also noticed when idling that the engine revs increase slightly when the AC comes on, is this normal?

Dbo · Post by **Dbo** » Fri Apr 19, 2013 11:16 pm

the revs increase is normal for aircon yes

you are sucking more power and idle goes up to compensate and you use more fuel with aircon on

BigTom · Post by **BigTom** » Fri Apr 19, 2013 11:17 pm

Cool, figured as much but thought I'd check. This 15 year old Prelude is by far my most technologically advanced car to date

craig_jdm · Post by **craig_jdm** » Sat Apr 20, 2013 5:19 am

If you manage to figure out what bit is broken by Sunday I can pick you up a replacement from the scrappies