I have notice my car not runnning smoothly on my 06 Mazda 5 sport for a while now with what I can only describe as a momentory loss of power. Dealer service came back no problem identified. Looking last night I realised that with the Climate control on the cooling fan is pulsing on for 5 seconds and then off for 11 continuously. The extra load seems to corrispond to the feeling of a momentory loss of power. I have switched the AC off and in my mind the car runs smoothly.

Spoke to the dealer this morning and they said it sounds like working fine as I have no engine management light.

Now I know its normal practice for fans to operate like this with AC/Climate however it seems to me that this constant pulsing for short periods seems excessive, especially as it effects the engine running.

Does anyone have any thoughts on whether this is reasonable or mind checking their own cars behavior. I don't think this is caused by the recent change in weather but has been an issue for at least 6 month

Cheers
Andy

 

Update. I took a look at a mazda 3 this lunchtime and its fans also seem to also pulse, however where mine spin for 5 seconds then stop completely for 11 the mazda 3 seems to spin at a reduce speed constantly but run faster for fives seconds before dropping back to half speed. Any thoughts appreciated as I only have a few weeks left on my warranty

Cheers
Andy

 

A/c pumps cycling on and off are usually a sign of low gas pressure. This won't show up any fault codes, so ask for the system to be checked. Not sure what the service requirements are on the a/c system so a re-gas might not be covered by warranty. Is the a/c working properly? try getting it to heat up the cabin and cool it down after.

 

Also, with warm engine idling, A/C cutting in and out will cause a perceptible temporary glitch in idle speed. With fast idle at 1500 rpm. A/C cutting in and out should not be noticeable on the tachometer.

 

Thanks for the feedback :-)

My dealer also suggested today that the car be booked in to check for low gas as the cause. They also checked a new diesel which showed a similar pulsing albeit on for 5 seconds and off for 20 (vs 10 on my petrol sport), so the car is now booked in for the a/c service as they recommend every 2 years.

Thanks Again

Andy