If its for cleaning, then the suction will not be strong. Low mode is for air cleaning purposes.
The vehicle does not have just one hose. A vacuum leak in any hose can cause low vacuum and the door will not operate properly. The leak could be under the dash or under the hood.
You can buy a vacuum hose at the store that you purchased your vacuum. If they no longer sale them you can check sites like eBay and Amazon. These sites offer low prices because you can buy from the seller charging the lowest price with shipping.
Vacuum hose leaking.
Using a set of gauges put the blue hose on the low side (larger hose), put the red hose on the high side (smaller hose), put the remaining yellow hose on a vacuum pump and let it vacuum for about 1-hour and if it holds then recharge the system adding both freon and oil.....
Many things can cause lag while driving at a low RPM but not at a high RPM even if it is not the vacuum hose disconnected from the EGR valve as it could be the fuel filter. It can also be the park plugs.
it has a low idle. Can also be a vacuum hose leak.
Get a set of a/c gauges and put the blue hose on the low side and the red hose on the high side, connect the remaining yellow hose to a vacuum pump..... Vacuum the system for 1-hour and let it sit for 1-hour and if it holds then add the correct amount of both freon and oil depending on the year, make and model.......
Check the EGR valve. Sounds like serious vacuum leak. Reminds me of when I left brake booster vacuum hose disconnected...
There is none. It needs to be evacuated with a vacuum pump on low side behind the front grill.
As far as opening and closing nothing, just make sure your hose is filled with water it is eaiser to begin vacuuming, normally we attach the hose to the vacuum that goes in the pool then attach the hose to the skimmer then begin vacuuming if we do not loose our prime, if the pressure gauge on the filter is reading low you can probaly can start vacuuming if it is reading mid to high pressure it sometimes is best to backwash before vacuuming.
Large hose is the low pressure hose.
There are two hoses which go to your compressor. One is small, one is large... the large one is the low pressure hose. Follow that one back to the metering device. That's your vacuum (low pressure) side.