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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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Weird blower/heater motor issue - is it normal?Views : 1884 Replies : 22Users Viewing This Thread : |
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Jun 20th, 2021, 12:32 | #11 | |
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I tested the vacuum on the manifold with my finger and it does seem to be ok. I tested the pipes by blowing through them and they also seemed ok BUT I replaced them with new flexi vacuum lines anyway up to the one way valves. I did buy new one way valves from Halfords (needed in a hurry) but the ones I bought didn’t seem to let any air through at all and I am returning as faulty. The ones already on the car seemed to work ok when I blew through them but not sure if that translates to good operation while the car is running so I am ordering some metal ones off eBay instead. So I had to reinstall the old ones and the problem isn’t fixed still so it might be the one way valves but I’m not sure. Is there any other part of the system I can check? I can see the lines go through the bulkhead but they aren’t easily accessible as they are under the heater pipes so I cant visually check them - is there any connections under the dash I can check? Any idea how I can check the vacuum to the heater flaps to see if that’s the problem rather than just replacing parts and hoping?
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Jun 20th, 2021, 13:36 | #12 | |
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It's pointless checking other parts of the system at this point as it seems your original valves are faulty from your description so i'd fit a new pair and see where you go from there. Once you've got those fitted (with the arrows on them pointing towards the inlet manifold), test the system and see what you've got.
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Jul 15th, 2021, 06:57 | #13 |
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Fitted the new valves and it didn’t make any difference - what else can I check?
The blowers literally go down to nothing when accelerating, they do seem to inversely match the amount of throttle input or engine load i am asking for. Light or no load, blowers on full, heavy load blowers zero. There does seem to be a bit of a lag though when they change which suggests to me it’s still a vacuum issue maybe??
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Jul 15th, 2021, 07:54 | #14 | |
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Also worth trying to narrow it down to a particular setting e.g. vents, feet or screen. If it only does it on one setting (not mixed such as vents/feet or feet/screen) then investigate the vacuum hoses to that serfvomotor and the servo motor itself.
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Jul 19th, 2021, 16:31 | #15 | |||
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What exactly am I checking on this part? Quote:
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Thanks for the help!
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Jul 19th, 2021, 17:25 | #16 | |
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Jul 22nd, 2021, 16:59 | #17 |
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Ok tried a few things after doing some more googling. The one thing that is for sure is that when I unplug this white vacuum lead and drive, if coasting I can hear it sucking air very well. When accelerating the vacuum sound from the hose itself stops completely. But where does this white hose go??
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Jul 22nd, 2021, 17:00 | #18 |
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I have tried capping off the air lines under the steering wheel (which I beleive control individual parts of the system) it doesn’t seem to make much difference.
When I accelerate the air transfers from the face vents to the floor vents when everything is connected.
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Jul 22nd, 2021, 22:24 | #19 |
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It looks like it should go to the reservoir Rob, yours looks different to mine and how i described it. Fairly sure the hoses under the steering wheel are for the ignition EZK unit and maybe the fuel ECU, also there will be two if you have cruise control that go to the brake pedal (and maybe clutch pedal) switches.
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Jul 23rd, 2021, 18:08 | #20 | |
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The picture I showed - is that a vacuum reservoir? Really unsure what to do now as its really hard tracing the vacuum back from the one way valves I originally thought were the issue.
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