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01 Pathfinder AC Problems


ryjaytay38
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I've got some air conditioning issues. I thought it needed to be recharged but it was perfect on full. Compressor engages everytime it's on. I know nothing about ac so I'm wondering what I can/should look for? I can drive to work and I'll have nothing for 5 miles and then it kicks on cool air. Other days, I'm driving and it is blowing like a blast furnace in my face for 15 miles. Any ideas of where to start would be sincerely appreciated as it's going to be 113+ for the next 8 days.

Thanks in advance!!

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Is yours the manual a/c or automatic? If you have a full charge and the compressor is working, problem is likely the temperature control door in the HVAC system. 

One test you can do without tools or gauge set, is to start the engine, turn on the AC and after a minute, carefully touch the pair of pipes at the firewall. The large one should be cold to the touch and the small one should be hot. If that is what you get, that indicates that the system is working properly. If not, then there is a problem in the system that requires more work to diagnose. 

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Mine is automatic. I just went out and tried what you said. Just to be clear, when you say the large pipe, you mean the pipe that has the the low pressure port on it? If that's the case, it is not cold at all. Is it time for an ac shop or is there a way to look into the temperature control door?

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Yes, the larger pipe has the low side port. If it isn't getting cold, that is telling me that either the refrigerant isn't flowing or flowing too much. Is the small pipe hot? Either way, it sounds like your problem is not the temperature door. 

With the AC on and engine running, the hub of the AC pulley is turning with the pulley, correct? If so, you will need a set of pressure gauges to see what is going on. General rule of thumb I have seen with most ac systems, with ambiant temperature about 80-90°f, the low side should be about 30-40 psi and high side about 200-250 psi. 

If both are low, then the charge is usually low. If both are high, then the system is usually over charged. If the low side is low, high side normal or high, usually a restriction on the system. Low side pressure high with high side low or normal usually indicates an expansion valve stuck open. 

If both the high and low are close to the same, usually indicates a failed compressor. Fluttering needles on the gauges, usually happens on the high side, indicates failing valves in the compressor. 

 

If the hub of the compressor pulley is not turning or starts and stops frequently, you have either a pressure switch or electrical problem. 

 

All this assumes that your AC has a proper charge +/- 1/2 pound of 134a refrigerant. 

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That is by far the most informative, helpful post I've ever seen on any topic on this forum! I'm going to Oreillys after work to get the gauges and check all of the pressures. I pulled my cabin filters yesterday for the heck of it, thinking maybe I'll have a little stroke of luck and this will solve my problems. I realized I had never changed them! Not something I'm proud of however, when I pulled them out and took a peek inside, I have no idea how any air at all was able to get into the cabin. It definitely made a difference when I pulled them and cleaned it out, but there's still something wrong that we'll find out tonight. It just doesn't have that "bite". It's not miserable driving around, but enough to where you're sweating. Definitely not where it needs to be.

I'll keep you posted on my findings and thank you again for the simple to follow
and incredibly informative post. I really appreciate it!!

Here's what it can look like if you neglect the air flow/filters inside your Nissan! Don't be me!

cabin filter.jpeg

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Mr Reverse,

I got the gauges and this is what they read. If I'm reading correctly, it looks like expansion valve stuck open? But when I shut of the ac and turned it back on, they were almost identical(failed compressor?) I refuse to pay a shop $500 or $1000 so what do you think? I've put a compressor, drier and switch in when I put a new motor in my Trooper so I'm sure I could do this, but I have no knowledge with an expansion valve other than people telling me it's a b---- to get to. I tried to put pics on but i resized it as low as I could and this thing says they're too big so here's what I had: the gauges stayed at about 90 on the low side and 110 on high side. I shut off the ac and turned it back on and they both stayed at right about 100. What does it tell you?

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Is the compressor hub actually turning with the AC on? 100 psi is pretty close to what I see for static pressure when the engine is off. 

It does seem like the expansion valve is open too much to give the needed pressure differential needed to work. 

 

Yep, dirty cabin filters are something that sneaks up and prevents the HVAC from working well, but usually the complaints I get where the filter caused troubles was low air flow from the vents. 

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Yeah the compressor hub is turning-looks completely normal. I had someone shut it off and turn it on while I watched and it looked totally normal. Should I start with the expansion valve? Or just do the whole thing? I guess if I can get away with a $30 part and some labor, it's better than having to shell out a few hundred. I don't know much about the valve. I'm guessing the system has to be evacuated to replace it, but I have a sneaking suspicion that there's more to it than pulling it out and dropping a new one in correct? I'm pretty sure the compressor is the original so I think his days are probably numbered as well. I think if I were to replace the expansion valve, I should probably do the orifice tube, and at the same time, I'm thinking I should maybe do the compressor in case it's starting to come apart internally. I don't want to put new parts on and contaminate them with a bum compressor.  Tell me what you would do. I'm way too indecisive 

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You will need to have the system evacuated. Then you can replace the expansion valve. It is simply remove the old and install the new. Though getting to it can be a bit harder than the instructions make it seem. I haven't done it with an R50, so don't have any tips there. Nissan doesn't use an orifice tube. The orifice tube and expansion valve do the same thing, they meter the liquid refrigerant into the evaporator, they just do it in different ways. The orifice is a fixed size and the flow is primarily controlled by cycling the compressor on and off. This is how American systems generally are. The expansion valve is located near the evaporator and works like a thermostat. It changes the flow rate according to the temperature of the evaporator. 

 

Usually it is a good idea to replace the dryer anytime the system is opened and parts replaced, but for something minor like an expansion valve I don't worry about it. Pulling a vacuum for about 15 min on the system before recharge works well enough to dry it out. 

 

As for the compressor, if it isn't making odd noises, I don't worry about it too much. With the engine off, I turn the hub by hand and if it turns with light resistance it should be fine. 

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I just got off work , went out and turned the compressor hub and it turns with slight resistance-not completely free, but not difficult to move. That would be nice to not have to replace the compressor. I'm trying to find an expansion valve and everyone has to ship them in. I have a hard time believing nobody in Phoenix has one but probably not a good chance on a Sunday night. I'll look online and otherwise I'll check Parts Authority in the morning and Advance Auto. Thanks for all your help. I really appreciate it!! I'll let you know how it turns out!!

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  • 3 weeks later...

Mr. Reverse, 

Finally got the correct expansion valve after 4 tries. Turned out to be a 2002 instead of 2001. Anyway, got the air working great and today I come out to the old blast furnace in my face. Put the gauges on and now have low side high and high side low. You said previously that that indicates an expansion valve stuck open. How can I "unstick" it? What other possibilities could it be?

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Sounds like the compressor isn't working anymore if the pressure is similar on both and close to the static pressure. You might want to have a shop evac  the system and make sure that you have a full charge. Just to eliminate the possibility of a leak causing poor performance. 

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