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Air is not blowing from vents...sometimes

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo's stylish, distinctive "P2" platform cars.

2001 - 2007 V70
2004 - 2007 V70 R
2001 - 2007 XC-70
2001 - 2009 S60
2003 - 2007 S60 R

VolvoKeep
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Air is not blowing from vents...sometimes

Post by VolvoKeep » Wed Sep 25, 2019 3:39 pm

Hi Everyone,

2004 S60 2.5T FWD
Air is not blowing from vents sometimes:

Symptoms: Car turns on with AC on, blower on full, both temp dials set to coldest (62) blue mark, vent either on manual or automatic. Blower motor is going full blast but air from vents is almost nothing.
IF the temp dials are then turned to a hot temp such as 80 for only a couple of seconds THEN dampers open up and hot air is full blast through all vents, THEN if temp dials are turned back to cold temp such as 70 air will continue to blow full blast for quite a few minutes then the air flow is shut off by some dampers again.

SOMETIMES when the car starts the air will blow full blast with no problems.

AT ALL TIMES, blower motor is going full blast and does respond to blower speed dial, switching on or off re-circulation has no effect, switching on or off AUTO mode has no effect.

Also IF the temperature dials are set to cool and the AC is turned off for a couple of seconds and then turned back on THEN the air will come through full blast but within about three seconds will be shut off again to practically no flow while the blower is still going full blast at all times.

This problem sounds very similar to other issues posted on the discussion board but I have not seen any diagnosis and cure of this issue.

My code reader will not read the CCM codes so I can not yet determine if there is a code stored. I can voltage check connectors but have not started that troubleshooting yet as I am hopeful that someone else has seen this and knows the culprit component.

Thanks for any suggestions you can give
VolvoKeep



DrDan
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Re: Air is not blowing from vents...sometimes

Post by DrDan » Thu Sep 26, 2019 12:39 am

This could be the evap temp sensor. It's a resistive sensor (PTC vor NTC, not sure which) meaning you can check it using a multimeter. Access is form the driver footwell. Cheap and easy to replace, but provides important input to the CCM so it won't work right if the sensor gives a false reading. I would start there.

I can look up details later if you need them. VIDA has the reference resistance also.



DrDan
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Re: Air is not blowing from vents...sometimes

Post by DrDan » Thu Sep 26, 2019 7:54 am

There's actually a thread that has the relevant info, along with a hint how you can find the resistance. There had to be, because finding the clue to that sensor here at MVS and consequently solving my climate control issues by replacing it was what brought me here in the first place :D

viewtopic.php?t=86426



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oragex
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Re: Air is not blowing from vents...sometimes

Post by oragex » Thu Sep 26, 2019 9:06 am

As above, it's a simple fix on the left hand driving cars www.youtube.com/watch?v=s1vIWTG9-Zw



VolvoKeep
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Re: Air is not blowing from vents...sometimes

Post by VolvoKeep » Mon Sep 30, 2019 7:19 pm

Thanks DrDan and Oragex , I will be able to get my hands on the car tomorrow to check it.



VolvoKeep
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Re: Air is not blowing from vents...sometimes

Post by VolvoKeep » Tue Oct 01, 2019 1:54 pm

Thanks
Thanks DrDan and Orangex. I don’t have VIDA but do have a service manual. I pulled the sensor and checked it against the values in the manual listed at the end of this post.

The sensor reads:
Ice water with digital thermometer 0C =8.4 kohms, (Should be appx 9k)
ambient air with digital thermometer 23C=3.01 kohms, (Should be appx 3k)
hot water with digital thermometer 40C=1.29 kohms (Should be appx 1.5k)

The manual only says that they should be approximately the values I have listed in the tables below with no tolerance or failure limits. The values I got could be interpreted as within tolerance for a common +/-10% NTC thermistor.
Note: Jimmy57 says that “freezing is 10K ohms +/- 200 and 25C/77F is 3K ohms range are the two I remember.” In post viewtopic.php?t=63739&start=10

Does anyone have knowledge of what the tolerance limits are?

The symptoms do not seem like the evap is freezing up because I can instantly change the air flow within seconds by cycling the AC on and off or by cycling the temp setting from low to high and back to low. It also occurs upon immediately starting the car on a hot day where the air flow will be full blast for 3 seconds then completely close off. There is no freezing of the AC lines under the hood and I can hear the damper doors closing and the air flow shutting off when this happens. If I cycle the AC off for three seconds and then on the air flow comes out full blast for about two seconds then within the period of one second it goes to basically no air flow while the sound of a whoosh and thump of the damper doors close. I can repeat this cycling repeatedly until I worry about short cycling the compressor. The same happens for turning both inside temperature controls from blue to red and back to blue again. Please do not get me wrong, until proven otherwise it could be some fault from the evap temp sensor but the symptoms that folks describe of slowly losing air flow are different than full blast to zero air flow and back again that the HVAC system is doing. My symptoms do seem like the post 76428 linked below but the OP never came back and stated if replacement of 30665118 fixed the issue.

Anyone else come across this? I prefer to not throw parts at symptoms but may if necessary.

For reference:
For the evaporator temperature sensor part # 30665118
From page 21592 of the service manual (without the connector connected):
-40°C = approximately 91.8 kohms
-35°C = approximately 66.3 kohms
-30°C = approximately 48.4 kohms
-25°C = approximately 35.7 kohms
-20°C = approximately 26.6 kohms
-15°C = approximately 20.0 kohms
-10°C = approximately 15.2 kohms
-5°C = approximately 11.6 kohms
0°C = approximately 9.0 kohms
5°C = approximately 7.0 kohms
10°C = approximately 5.5 kohms
15°C = approximately 4.3 kohms
20°C = approximately 3.5 kohms
25°C = approximately 2.7 kohms
30°C = approximately 2.2 kohms
35°C = approximately 1.8 kohms
40°C = approximately 1.5 kohms
45°C = approximately 1.2 kohms
50°C = approximately 1.0 kohms
55°C = approx. 826 ohms
60°C = approx. 688 ohms
65°C = approx. 576 ohms
70°C = approx. 485 ohms
75°C = approx. 409 ohms
80°C = approx. 347 ohms
85°C = approx. 296 ohms
90°C = approx. 253 ohms
95°C = approx. 217 ohms
100°C = approx. 187 ohms

From page 21598 of the service manual (using VIDA to measure)
-40°C = approximately 91.8 kohms
-30°C = approximately 48.4 kohms
-20°C = approximately 26.6 kohms
-10°C = approximately 15.2 kohms
0°C = approximately 9.0 kohms
10°C = approximately 5.5 kohms
20°C = approximately 3.4 kohms
30°C = approximately 2.2 kohms
40°C = approximately 1.5 kohms
50°C = approximately 1.0 kohms
60°C = approximately 0.7 kohms
70°C = approximately 0.5 kohms
80°C = approximately 0.3 kohms
90°C = approximately 0.2 kohms

This post seems similar to the symptoms in my 2004 S60:
2006 XC70 A/C air flow blocked
viewtopic.php?t=76428



DrDan
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Re: Air is not blowing from vents...sometimes

Post by DrDan » Tue Oct 01, 2019 11:58 pm

Given your readings, I would rule out the evap Sensor. Mine was crazily off, yours seems quite OK but I also do not know the tolerance.
Also the symptoms are different. My problems were definitely caused by the evap freezing which does not seem to be the case here.

VIDA has a function to calibrate the damper doors, maybe this could help if the issue is pertinent to that but really this is an educated guess at best.



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