Intermittent AC Clutch and P0300

[Medic5]

Honestly since the first month I had this car, from 9 miles. My UltraGauge would toss me maybe once every few months a P0300 Error Pending. I would simply clear it and no issues. Now the past month, I'm getting P0300 Error pending and occasionally the check engine light will come on and I have to clear it out.

I notice that some days the idle is smooth, and some it's rough. Not noticing anything that specifically causes it.

I should note this is a 2013 Mazda 2 Sport with 68,500 Miles. It has a lot more engine hours on it as I work out of it, and on road trips live out of it. I lived out of it for almost 4 months in the summer a year and a half ago on a long trip. AC was on a lot!

I have also noticed this last month that one day while driving the car just started blowing warm air. My first thought was "oh no..." You know! After driving it around bummed out, it randomly kicked on on the highway. Worked the rest of the day. And the days after. I thought I was in the clear, blowing around the 50 degree mark.

The last 2 weeks now, it's been increasingly intermittent. Especially at idle. It might engage the clutch cycle for a half hour or more, and then just randomly disengage and not re-engage for sometimes 30+ minutes. Oftentimes if I drive hard, it will kick back on. I have noticed that the problem occurs more often during the mid day when it's the hottest.

I have checked the pressure on the Low Side using a AC Recharge can, but did not need to add any, as the pressure was within limits for the current temperature.

I'm a little worried to be using my car daily as I'm afraid I may save the core AC components and make this even more costly. The dealer wants way too much to look at it, and said I "haven't done an Induction Service on it?!", I said that I have been following the service manual. Replacing things as needed, changing fluids and lube as indicated. Regular oil changes ways synthetic. Tank of 93 Gas for every 8-10 fill ups. I will randomly clean parts of the car and under the hood. I do weekly PMs, and although I push my M2 to it's limits sometimes, I take care of it. They said I should've had carbon cleanings done every 20k miles or so. My car before this was a 1994 Ford and I didn't have to do that...

Someone recommended SeaFoam but it sounds like a lot of hype to me.

Any ideas? I'm not sure what to do with it currently.

 

[hli]

Those two different issues should be isolated. P0300 points to a misfire, so it may be coils, injectors, etc. The A/C working intermittently might be the clutch going out, or maybe the condenser temperature sensor. The sensor can be reached from the passenger footwel panel; I'd try sticking in a resistor (I forgot if high resistance meant higher temperature or low resistance). If that fixes the issue, you need a new sensor.

 

[utmorpheus]

Change your plugs. At near 70k it's time, even with the iridium plugs. I have yet to see a direct injection engine not eat them up by that time frame.

The A/C is likely either a temp probe problem as hli said, or a bad pressure sensor in the A/C line. Either way I'd have an independent shop look at it. Dealer is absolutely insanely priced for anything A/C related.

 

[flatlander937]

Change your plugs. At near 70k it's time, even with the iridium plugs. I have yet to see a direct injection engine not eat them up by that time frame. Our cars are not direct injected BTW.

The A/C is likely either a temp probe problem as hli said, or a bad pressure sensor in the A/C line. Either way I'd have an independent shop look at it. Dealer is absolutely insanely priced for anything A/C related.

X2 on plugs, mine were throwing random misfires at 49k and they looked perfectly fine.

On the A/C issue you need to start with backprobing the compressor clutch wire, make sure its getting commanded on. If it is(and not engaged) compressor is bad. If its not getting a signal look at pressure switches and/or evap temp sensor.

Looking at low pressure alone won't tell you a thing. Could be a restricted expansion valve + air in the system which would cause high high-side pressures and acceptable low side pressures. You need to either have a scan tool to watch the evap temp and refrigerant pressure sensors or you won't know which is being triggered to turn it off.

If you're going to get the AC recharged you do NOT use those stupid cans. You need to evacuate the whole system, pull a vacuum for 20-60min to remove moisture from the system, then charge it assuming it holds vacuum for 10+min when done for a basic leak test.

I see more people mess up tons of stuff trying to save money on AC work than anything else. Leak on the condenser will leak refrigerant out and oil, keep charging with a little can you end up wrecking the compressor which will spit metal shavings through the whole system. Then plan on replacing the condenser and expansion valve/orifice tube/receiver-drier depending on the type of system.

 

[Medic5]

Well, I changed my spark plugs about 1000 miles ago actually trying to fix the error with no luck.

As soon as I figure out exactly where to in the Mazda2, I'm going to cycle through half can of SeaFoam into the throttle body and hopefully that will help some until I can get someone to clean the intake valves completely.

I didn't actually use the Refridgerant in a can, I just used the gauge off of one. But I will heed yor advice and either have someone look at it, or I'll see what it costs to replace the clutch. I'm suspecting it may be that since it intermittently engages and will randomly disengage for a random amount of time. And when it's engaged it's blowing cold air. So it's not the compressor or Refridgerant.

I'm also going to monitor some value on my UltraGauge the next few days to see what values are fluctuating at idles especially rough ones.

I appreciate your help all!

 

[flatlander937]

Low refrigerant will cause it to cycle constantly/intermittently. You really need to watch high and low sides before making that assumption. Could be a restriction causing high side to shoot up quickly.

Is the cooling fan working? And/or does A/C work while cruising highway speeds or does it still it off?

 

[Medic5]

It mostly does this when Idle. I drove 600 miles over the weekend and had it happen twice while driving. But lasted maybe 5-10 minutes each time. Sometimes during idle it happens multiple times In a few hours. I just changed the cabin air filters to see if it helps at all today. Will advise. Will also be sea foaming my car today IF I can find the right vacuum hose. Not many diagrams that I can find.

Edit: the cooling fan behind the radiator does work.

Low refrigerant will cause it to cycle constantly/intermittently. You really need to watch high and low sides before making that assumption. Could be a restriction causing high side to shoot up quickly.

Is the cooling fan working? And/or does A/C work while cruising highway speeds or does it still it off?

 

[Camshaft]

Interesting info in here. I was going to wait until 100k to replace my plugs, but I might go ahead and do it at my next service (72k), especially if I go with a tune.

 

[flatlander937]

Definitely sounds like low charge may be the issue. Mine is starting to get "meh" at idle in super hot weather but not cycling wildly.

You could most likely get it evacuated and charged and not have any problems for several more years.

Remember to instruct whoever does it to pull a vacuum for at least 45min+, overnight is even better.


And FYI by factory manual plugs are due at 75 or 80k IIRC. Definitely don't wait til 100k.