AC and Fan Problem 3.0 - Ranger-Forums - The Ultimate Ford Ranger Resource


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  #1  
Old 08-18-2016
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AC and Fan Problem 3.0

2006 3.0, just had a new motor installed. AC and Blower both are cutting in and out at highway speeds 65 and up. I know the AC is supposed to do this when you floor it, but this seems more related to speed than rpm/acceleration. Any ideas ?
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  #2  
Old 08-18-2016
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I'll add this. City driving with selector in the face/floor position, rpms up to 3k and speed up to 45 is cold. Seems to be highway speeds only ?
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  #3  
Old 08-18-2016
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Reads like a Vacuum problem.

The vents in the dash are held in their various positions by engine vacuum.
Default position is Defrost, so low or no vacuum will cause air to flow to Defrost vents.
Because engine vacuum is not consistent here is a vacuum reservoir that stores vacuum to hold these vents in position while engine is under load(low vacuum), if reservoir or vacuum line has a small leak then system simply runs out of vacuum during periods of longer low vacuum.

See if vents are switching to defrost vents at highway speeds.

As far as temp, AC system could be low on refrigerant.
A new motor can be installed without opening AC system but moving the AC lines around could have caused a leak.
Or if system was depressurized for the install then it should have had a new dry/accumulator installed when it was refilled, and it may need a top up.

Last edited by RonD; 08-18-2016 at 09:24 AM.
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Old 08-18-2016
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I noticed on the way home when this happened it seemed to go to defrost, I guess that's what makes it feel like the blower fan was quiting. Time to look for a vacuum leak.
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Old 08-18-2016
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If you look at the passenger side firewall, engine side, by the AC and blower unit, you should see a black plastic vacuum line, coming out of the firewall, it is made of hard plastic so may look like a wire.
There is often a Grey plastic vacuum line with it.

The Black line runs to the vacuum reservoir, it looks like a black ball.
This line often gets near exhaust or just cracks, it can be repaired with correct size rubber vacuum hose
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  #6  
Old 08-19-2016
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Found a couple of spots on the plastic hose from the reservoir to the manifold. I wondering if I could replace that with rubber or if there was need for the plastic hose.
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  #7  
Old 08-19-2016
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Wrapped the holes with gorilla tape for a quick test and hit the highway, no problems. It rubbed through against the metal ac fitting on the compressor. Thanks !
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Old 08-19-2016
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Good work

Thank for posting the fix
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  #9  
Old 09-07-2016
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Started out with a multi-factor problem, so I started from the top. My main point of contention

Fan clutch had gone out and radiator had cracked so I started there and got those two things replaced. That at least got my AC system working again (due to fan clutch, right? Before, it was clicking but would never blow cold air.).

But once it started blowing cold again, it was only out of the defrost vents, but maybe the dash at sparse, random intervals. Such as a few minutes after startup and then once every 5-10 minutes for a minute or so at a time. Researching this, I come to find I have no vacuum controlling the dash air mixers. So I traced the lines...

My black vacuum line had some heat stress and age degradation just off the vacuum reservoir headed towards the firewall. Clipped out the gnarly bits and stuck both clean-cut ends in an oversized splice-connector (the old hard brittle plastic line is too small to use barbed connectors IMHO), and used electrical tape super-snugly to hold the hose inside the splice piece. VOILA. Dash control diverts air properly again and I didn't see the AC drop out...yet (haven't gone out for more than 5 minutes but I wanted to at least share that identifying and repairing this vacuum leak did get dash air mix control back). At least if the AC does drop out again I know it's probably just a relay or pressure switch issue since my system works well when it is active.
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