2005 Mazda 3 Sport GT Air Conditioning Issue

Had an issue with the AC on the weekend. Driving Hwy 401 at speed and approximately 3200 rpm for 3 hours and AC is blowing lukewarm air. Set fan at speed 4 and interior air recirculated. No change for whole trip. Next morning left house and turned AC on and it appeared to be normal. When there was no cold air it almost seemed like the compressor was not working but I can't confirm that. Car is now at dealer for 2 days and they are struggling to find the issue. I think they are going to try the evaporator temperature sensor tomorrow. Anyone have any other ideas?

Have they checked the refrigerant pressure? If you have a slow leak and are losing refrigerant, the compressor won't come on once there's too little in the system.

They ended up replacing a cable that has a resistor on it between the computer and the AC controls....seems to be working fine right now but a long drive on the hwy at high temperatures will tell if this was the issue. Everything else in the system was working fine with no trouble codes. Freon was bang on.

the 04 and 05s had a smaller evaporator and air moving past it is too turbulent for even flow... mazda came out with a special cabin filter that has diffuers to fix this issue.. they also came out with diffusers only, no filter.... there is no aftermarket equivalent

you need to order EITHER:
BN8P-61-J6X diffuser kit (if you don't care about having a cabin filter and never want to deal with changing it)
BP8P-61-J6X cabin filter set with diffuser

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Originally Posted by TheMAN

the 04 and 05s had a smaller evaporator and air moving past it is too turbulent for even flow... mazda came out with a special cabin filter that has diffuers to fix this issue.. they also came out with diffusers only, no filter.... there is no aftermarket equivalent

you need to order EITHER:
BN8P-61-J6X diffuser kit (if you don't care about having a cabin filter and never want to deal with changing it)
BP8P-61-J6X cabin filter set with diffuser

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I should have mentioned that they also replaced the cabin filter with diffuser. Seems to be working okay right now but the weather has also cooled off. Need another super hot day to see if it really has corrected the problem.

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Originally Posted by intruder1500

I should have mentioned that they also replaced the cabin filter with diffuser. Seems to be working okay right now but the weather has also cooled off. Need another super hot day to see if it really has corrected the problem.

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So , we had another hot day...40 degrees with the humidity. After 2 hours of driving with half stop and go the air starts to get hotter in the car. Try full fan and recirculate to no advantage. I then realize that the air from the vents is hardly nothing. Hmmmm cabin filter is covered in frost and not allowing air to pass through or fan motor bearing is slowing down when it gets really hot. Continued on trip and turned off AC and fan to zero. Waited an hour , turned on AC and fan speed back to normal and AC working fine. Back to the dealer....I think first thing to try is to take out cabin filter and diffuser. Anyone have any comments?

your evaporator had frozen... at this point, you either have a line restriction, bad expansion valve, low refrigerant, or simply a bad thermo switch... mazda issued a TSB for this problem but only applied it to the newer 1st gens... it involved using the diffusers and a resistor inline with the thermo switch... it works and I bet that will fix it

the thermoswitch connector is that piece of wire that comes out of where you access the cabin filters, not too hard to get to... replacing the thermo switch itself is much harder though (dashboard removal is involved)

you can try buying the resistor (not cheap), but it's plug and play:
BPY1-61-545A

Quote:

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Originally Posted by TheMAN

your evaporator had frozen... at this point, you either have a line restriction, bad expansion valve, low refrigerant, or simply a bad thermo switch... mazda issued a TSB for this problem but only applied it to the newer 1st gens... it involved using the diffusers and a resistor inline with the thermo switch... it works and I bet that will fix it

the thermoswitch connector is that piece of wire that comes out of where you access the cabin filters, not too hard to get to... replacing the thermo switch itself is much harder though (dashboard removal is involved)

you can try buying the resistor (not cheap), but it's plug and play:
BPY1-61-545A

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Thanks TheMAN, you mentioned newer 1st generation...that does not apply to my 2005? Any chance you know the TSB number? It makes perfect sense that the evaporator was frozen....low air movement from the vents even on fan speed 4. Also when we got home after the AC being back on and working for 30 minutes water was puking out from the drain like crazy. We'll see how it goes back at the dealer.

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Originally Posted by intruder1500

Thanks TheMAN, you mentioned newer 1st generation...that does not apply to my 2005? Any chance you know the TSB number? It makes perfect sense that the evaporator was frozen....low air movement from the vents even on fan speed 4. Also when we got home after the AC being back on and working for 30 minutes water was puking out from the drain like crazy. We'll see how it goes back at the dealer.

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TheMAN, just an additional info PS - resistor was replaced already so that's not the issue.

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Originally Posted by TheMAN

your evaporator had frozen... at this point, you either have a line restriction, bad expansion valve, low refrigerant, or simply a bad thermo switch... mazda issued a TSB for this problem but only applied it to the newer 1st gens... it involved using the diffusers and a resistor inline with the thermo switch... it works and I bet that will fix it

the thermoswitch connector is that piece of wire that comes out of where you access the cabin filters, not too hard to get to... replacing the thermo switch itself is much harder though (dashboard removal is involved)


you can try buying the resistor (not cheap), but it's plug and play:
BPY1-61-545A

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Well....that only leaves the thermoswitch and expansion valve....12 hours labor for the switch....AC works fine at less than 40 degrees C so I don't think $1500 plus is well spent on a 2005 even though I luv my car and treat it like its my 3rd kid. My biggest fear is to spend all that money and find out that the AC issue is normal at these higher temps ( 2004 and 2005 are noted for their poor AC performance ). Its a second car that doesn't see any winters so I'll leave it for now. Thanks for all the feedback from everyone.

so this is the resistor you "replaced"?
https://d354nuoz4t18d4.cloudfront.ne...?cb=1533751148
It doesn't exist from the factory!

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Originally Posted by TheMAN

so this is the resistor you "replaced"?
https://d354nuoz4t18d4.cloudfront.ne...?cb=1533751148
It doesn't exist from the factory!

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It was the part number you provided for the resistor in a prior note BPY1-61-545A....done by the dealer and listed on the workorder. It was installed along with a new diffuser / cabin filter. I cannot confirm the picture as I did not install it.

Ok, since it was installed, try taking it out and see if there's any difference... the resistor changes the thermo switch reading by 1 degree, which can affect how long the compressor is run... it simply unplugs, as shown in the pic... it's connected inline with the thermo switch... after removing it, you'll need to reconnect the thermo switch directly back into the wiring harness

If it was me (I have an 05) I would sell or trade in the car once cooler weather will be the norm.

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Originally Posted by TheMAN

Ok, since it was installed, try taking it out and see if there's any difference... the resistor changes the thermo switch reading by 1 degree, which can affect how long the compressor is run... it simply unplugs, as shown in the pic... it's connected inline with the thermo switch... after removing it, you'll need to reconnect the thermo switch directly back into the wiring harness

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It was doing the same thing with or without the resistor so removing it again will make no difference.

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Originally Posted by Google

If it was me (I have an 05) I would sell or trade in the car once cooler weather will be the norm.

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You probably would not understand the affinity I have for this car. Owned since day one with 250,000 kms now....car is like new except for high outside temperature 40 degrees plus AC issue....otherwise its fine. A sale is never going to happen ....well maybe never....

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Originally Posted by intruder1500

It was doing the same thing with or without the resistor so removing it again will make no difference.

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was this before or after the diffuser equipped filters were used?

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Originally Posted by TheMAN

was this before or after the diffuser equipped filters were used?

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Resistor and diffuser were both installed at the same time ( and for the first time ) when the problem first appeared.

then you don't even know if it would make a difference or not!

you would only know if there are differences if you tried one thing at a time, not all at once... this is common sense/typical scientific method

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Originally Posted by TheMAN

then you don't even know if it would make a difference or not!

you would only know if there are differences if you tried one thing at a time, not all at once... this is common sense/typical scientific method

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Thanks for your advice. I had planned to have the diffuser / cabin filter removed at the next oil change. Why, because the car never had a cabin filter for the first 160,000 kms from the factory. I'm wondering if the diffuser is slowing down the flow of air too much and causing the evaporator to freeze up. Additionally, our current temperatures and humidity....40 plus... may just be too much for the AC unit to handle. Anyways, that's my next step plan.

no, the diffuser is meant to distribute the air flow better, because without it, air flow is turbulent... that's why mazda issued bulletins to fix poor A/C performance in the 04s... the 2005 SP23 model in the US came with a cabin filter but also with the diffuser for the same reason... all 05s in USA and Canada came with the diffuser

the resistor never came from the factory and that is the only true variable causing the frozen evaporator issue further, aside from improper refrigerant charge, I believe... the resistor was meant to prevent the better evaporator used in the 06-08 from working too well (cool so much, it freezes)... the 04 never came with the better evaporator, and most 05s don't either... only ones produced (end of the run) during mid 2005s were

Quote:

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Originally Posted by TheMAN

no, the diffuser is meant to distribute the air flow better, because without it, air flow is turbulent... that's why mazda issued bulletins to fix poor A/C performance in the 04s... the 2005 SP23 model in the US came with a cabin filter but also with the diffuser for the same reason... all 05s in USA and Canada came with the diffuser

the resistor never came from the factory and that is the only true variable causing the frozen evaporator issue further, aside from improper refrigerant charge, I believe... the resistor was meant to prevent the better evaporator used in the 06-08 from working too well (cool so much, it freezes)... the 04 never came with the better evaporator, and most 05s don't either... only ones produced (end of the run) during mid 2005s were

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Your Quote: " all 05s in USA and Canada came with the diffuser."....mine must be the exception for 2005 as it did not have the diffuser or a cabin filter from the factory. As an additional note I was told by a 3rd party that the purpose of the diffuser was also to slow down the flow of air over the evaporator to allow the air to get colder.

Hi Everyone, I have been the first and only owner of a US 2005 Mazda 3 2.3L (2004 manufacturing date). The car is in great condition but the remaining pain is the A/C (manual A/C version).

9 years ago I did the mod discussed here https://www.mazda3forums.com/threads...cost-1.244365/
BTW: if anyone is interested, I still have the saved PDF from this thread with photos and better description - now the link to PDF does not seem to work anymore. The mod works but it caused the evaporator freezing a few years ago during a family trip. The situation meant no AC for a good while during the trip in extremely cold weather and I was cursed by the family. Effectively, I have not used the mod since.

BTW: prior to the mod, I installed the Mazda TSB diffuser but in my experience it did not make any difference. I ended up installing the post 2005 models air cabin filter instead (to at least get the benefit of cleaning the incoming dust).

I am now dealing with some AC leaks (substantially located; most likely not requiring the evaporator work but it is a slight possibility). All in all, I was thinking that this is my only opportunity to go the hard way (fully realize the pains of disassembling the center console) and replace the evaporator with the larger one (i.e. with the post May 2005 model) to finally start enjoying the AC that works. Having now read this thread, I started doubting this route though as I see that the larger evaporator is more likely to freeze. Could you please help me with these questions:
(1) Will adding the Mazda BPY1-61-545A resistor fix the evaporator freeze issue in systems with a larger evaporator?
(2) Are the the larger evaporator and potentially the resistor the only parts to be changed/added?
(3) Will the larger evaporator fit the large white plastic case - I think the answer to this is YES because I checked the 2005 and 2006 catalogs and they are showing as identical part numbers.
(4) Should I keep the air filter or some sort of a diffuser option will still be needed/recommended?

Many thanks for help with this!

Final note: if anyone needs the evaporator dimensions (e.g. in Europe they specify the dimensions frequently), here are two options that are coming up in my search for this car:
i) Bigger one: width: 237 mm; height: 245 mm; depth: 58 mm; part number should be CCY3-61-J1Z as I can see in Mazda catalog although it then further shows as superseded by CC43-61-J10
ii) Smaller one: width: 228 mm; height: 218 mm; depth: 48 mm; part number should be BPYK-61-J1Z - it shows as installed in Mazda 3 pre May 2005