Air con question

[Kev555]

Hi second quick question of the day. I went to get my air con recharged this morn. The Guy doing the recharge thought there might be what he called " a bit of a blow back" on the compressor while recharging it as the gauge dropped below the desired level for his liking. It held the charge ok but we were thinking the air could be cooler out of the vents. I noticed the compressor keeps switching off and on every few seconds, is this normal?

 

[Dino Dino Bambino]

The compressor should stay on for several seconds and then cycle off for a second or two. If yours is short cycling all the time, it's likely the AC hasn't taken up enough refrigerant to build the necessary pressure in the system.
If you still have the original drier and live in a humid climate, it may have become clogged up either by debris or by broken down desiccant. Therefore It might be a good idea to replace the drier and also replace the orifice tube at the same time.

 

[Kev555]

Thanks Dino, the mustang came from a dry dusty climate (Dubai) about a year ago, it only cycles for about 3 seconds and off for about 4 seconds roughly. Before recharging the clutch wasn't turning on at all.

 

[Juice]

Which side dropped lower than his liking?

Based on what you said so far:
1 System was empty.
2 Charged it and it acts like it is low on charge
3 compressor cycles like the system is low.
4 not cold enough, like it is low.
Sounds like the orifice tube is partially blocked. This would drive the low side reading low, and cause the lack of cooling.
Without knowing the actual pressure readings, this is a guess.
If you put the cabin fan on #4, no recirculation, the compressor should run longer and cycle less or not at all.

 

[Kev555]

Thanks juice I will try that. I think from memory it was the low side of the gauge was rising and falling with the compressor cycle. He pointed out the Gauge was dropping down lower than he would like at points in the cycle. I just handed £80 for a re-gas as the system wasn't totally empty according to the air con guy and he said it wasn't leaking so I let him fill it. I suppose theres no way to change the orifice without him taking the gas back out of the system? I suspect you have guessed right the way you described it and what I witnessed today while the guy was filling it. Another £80 to shell out at some point looks like after parts.

 

[Dino Dino Bambino]

Thanks Dino, the mustang came from a dry dusty climate (Dubai) about a year ago, it only cycles for about 3 seconds and off for about 4 seconds roughly. Before recharging the clutch wasn't turning on at all.

I shipped mine from Al Ain UAE to Cyprus 5-1/2 years ago. It was originally registered in Sacramento CA before it was exported to Dubai. I bought it in Dubai 8-1/2 years ago and "exported it" to Al Ain (Emirate of Abu Dhabi). It must hold a record having been registered four times with different plates.
Yours definitely sounds like it doesn't have enough refrigerant in the AC system.

Thanks juice I will try that. I think from memory it was the low side of the gauge was rising and falling with the compressor cycle. He pointed out the Gauge was dropping down lower than he would like at points in the cycle. I just handed £80 for a re-gas as the system wasn't totally empty according to the air con guy and he said it wasn't leaking so I let him fill it. I suppose theres no way to change the orifice without him taking the gas back out of the system? I suspect you have guessed right the way you described it and what I witnessed today while the guy was filling it. Another £80 to shell out at some point looks like after parts.

Unfortunately the system will need to be emptied again in order to replace the orifice tube and the drier (do not skip this part). After reassembly the system will need to be vacuumed to remove all moisture and then recharged.
It's unfortunate you had to spend $80 to find out that your AC system wouldn't charge properly but you had no other option at the time.

 

[86GT351]

The compressor should stay on for several seconds and then cycle off for a second or two. If yours is short cycling all the time, it's likely the AC hasn't taken up enough refrigerant to build the necessary pressure in the system.
If you still have the original drier and live in a humid climate, it may have become clogged up either by debris or by broken down desiccant. Therefore It might be a good idea to replace the drier and also replace the orifice tube at the same time.

Good points. If it is broken down, I would also suggest flushing the remaining components of the system.

 

[Kev555]

Thanks for the advice fellas, I will get the parts ordered up from rock auto and get it done before the summer arrives.

 

[Pentalab]

The compressor should stay on for several seconds and then cycle off for a second or two. If yours is short cycling all the time, it's likely the AC hasn't taken up enough refrigerant to build the necessary pressure in the system.
If you still have the original drier and live in a humid climate, it may have become clogged up either by debris or by broken down desiccant. Therefore It might be a good idea to replace the drier and also replace the orifice tube at the same time.

My compressor stays on for as long as I have it turned on. Is there desiccant (aka silica gel) in there somewhere ?
Desiccant can absorb 40% of it's weight...with moisture, that's it. Then it turns rock hard..and has to be tossed..and replaced. Typ AC units just dump the moisture onto the asphalt.