Automotive Air Conditioning Information Forum

I recently picked up a 2008 Nissan Altima as a commuter car for it's fuel economy. When I first got it the AC blew icicles. After a couple of weeks the air stopped blowing cold and it seemed like it was much cooler out of the passenger vents. I thought it was a blend door issue so I tore the dash apart and realized that I only have one blend door. I do not have dual climate control. I decided to add 1/2 can of freon and noted an immediate boost in cooling. I went ahead and added the rest of the can and drove it for a day. When I turned the car off, the AC was cooling, but when I started the car the next morning, it was blowing warm again. I checked the compressor and the clutch was not engaged.

I'm not exactly sure what or how to test. My understanding from reading is that if it is too low on refrigerant, the compressor may not kick on. I can try adding more freon, but doesn't the compressor need to be running in order to suck the freon into the system? I apologize of these are remedial questions. I can get a set of gauges and vacuum pump from the local parts store if needed.

At first glance it would seem you have a leak.
1. We sincerely hope that the can of refrigerant you added was just plain refrigerant, and did not have sealer . NEVER use sealer, it will gum up the system and cause more harm (think $$$) than good.
Assuming there was no sealer, it seems that you lost at least a full can of 134 rather quickly. Please let us know if the can had sealer.
2. Do not add any more until we can find the leak

" My understanding from reading is that if it is too low on refrigerant, the compressor may not kick on. I can try adding more freon, but doesn't the compressor need to be running in order to suck the freon into the system? I apologize of these are remedial questions. I can get a set of gauges and vacuum pump from the local parts store if needed."

3. The low pressure switch will not let the compressor turn on if the system is low on freon. This is because the oil for the compressor travels around with the freon, so if there is little or no freon, the comp will burn up due to lack of oil.
4. A set of manifold gauges would be your best friend right now because knowing the pressures in the system will aid in diagnosis.
5. Another tool that will be nearly indispensable is an electronic freon leak detector sniffer. If the gauges show any remaining pressure at all, then you can use the sniffer at every joint, connection, fitting,etc. Also, since it is hard to get at the evaporator under dash, you would sniff the water drain tube under the car, since freon is heavier than air and will sink down into the drain tube.
Also, you can remove the belt from the compressor and put a shower cap over the comp overnight, then sniff inside the cap the next day to see if the comp shaft seal is bad. Also, look around for oil stains at any fittings, if freon escapes usually some oil goes with it and leaves a tell-tale oil stain. If any fluorescent dye (yellow-green) was ever used in the system, look for stains of this color.

6. If the gauges show close to zero psi, then add a half can of 134 and then sniff right away until you find the leak. The pressure in the can of 134 is 70 psi, so if you have near zero psi in your system, it will push itself into your system without help from the compressor. An even slicker method is to invert the can and charge the high side with half a can of liquid 134. It will push itself in and distribute itself
7. Then report back

No sealer was added by me. I received a little help from this site a few years ago so I knew not to use sealer. My concern is that the previous owner just dumped a bunch of freon in it to sell it. I have no clue if he or anyone else added sealer.

I just ordered a freon sniffer. It should be here tomorrow.

Well if you did not add any, we are off to a good start. We'll take it one step at a time.

Assuming you can find the leak, we can walk you thru a repair, then you would vacuum down and recharge by weight and you would be good to go.
Look under the hood there should be a label which gives the amount of 134 required, and maybe even the amount of oil.

The specs that I have for your car indicate 18 ounces net weight of R-134a and 5 fluid ounces of PAG-46. As mentioned, if you have an under-hood decal with different specs, the decal takes precedence.

jtupper wrote: ↑Tue May 03, 2022 11:31 am I went ahead and added the rest of the can and drove it for a day. When I turned the car off, the AC was cooling, but when I started the car the next morning, it was blowing warm again. I checked the compressor and the clutch was not engaged.

The system might very well have a leak someplace as already mentioned. But have you checked the gap between the clutch plates (if you can get a feeler gauge in there)? The gap should be around 0.020" +/- 0.005". If it's out of spec, the clutch might engage occasionally or not at all. If it's too wide, you'll need to remove one or more shims to adjust it.

JohnHere wrote: ↑Wed May 04, 2022 8:20 am The system might very well have a leak someplace as already mentioned. But have you checked the gap between the clutch plates (if you can get a feeler gauge in there)? The gap should be around 0.020" +/- 0.005". If it's out of spec, the clutch might engage occasionally or not at all. If it's too wide, you'll need to remove one or more shims to adjust it.

I haven't checked the gap but I can get to the compressor from underneath or the wheel well. There isn't much access from the top. The sniffer should be here today and I'm going to get a set of gauges. Hoping to have more info this evening. I'm fairly certain I have a leak somewhere...just hope its not the evap.

jtupper wrote: ↑Wed May 04, 2022 8:29 am I haven't checked the gap but I can get to the compressor from underneath or the wheel well. There isn't much access from the top.

It's definitely worth checking while you're at it.

jtupper wrote: ↑Wed May 04, 2022 8:29 am The sniffer should be here today and I'm going to get a set of gauges.

Tim at ACKITS.com carries some excellent Manifold Gauge Sets.

jtupper wrote: ↑Wed May 04, 2022 8:29 am I'm fairly certain I have a leak somewhere...just hope its not the evap.

Sometimes, road debris or even a stone can kick up and hit the condenser, causing a leak. Suggest going over the condenser first with the sniffer. Also, visually inspect it for signs of oil or a greenish substance, which is a UV dye that's sometimes added to a system for the purpose of highlighting leaks.

JohnHere wrote: ↑Tue May 03, 2022 2:29 pm The specs that I have for your car indicate 18 ounces net weight of R-134a and 5 fluid ounces of PAG-46. As mentioned, if you have an under-hood decal with different specs, the decal takes precedence.

Is there a conversion to determine how many ounces of canned freon equates to 18 oz. net weight without weighing it? Is it as simple as 1-1/2 12 oz. cans is what is needed? It doesn't seem like much.

No conversion needed.
But with the 12 oz cans, you can seldom get it all out, typically leaving behind 1-2 oz.

Please recall that you do not have to have a full charge to find your leak. One can will do