My Mini Split Air Conditioner Won’t Start

Written by Terry M:

Problem:  My mini split air conditioner worked great last year when I purchased it and had it installed.  This year I turned on the inside unit and it only blows room temperature air.

Solution:  This is a pretty standard complaint for Springtime consumers.  There are two different strategies to try to find the problem.

1.  Check Electrical Wiring:  Make sure the outdoor condenser is operating while the power is “ON” for the indoor evaporator.  If the outdoor condenser is not operating check the outdoor electrical disconnect.  If it is a fused box make sure the fuses are still operational and the circuit breaker in the electrical box is “ON”.

Check that power is reaching the condenser, either 110 volts or 220 volts depending on the size of your condenser.  There are stickers on the outside condenser that will tell you the proper voltage.

You can then check that the contactor is receiving power between the terminals C and Y.  This should read 24 volts.

If both of these check out properly then it is probably a refrigerant problem.  If the evaporator is calling for power and the unit is low on refrigerant, the low pressure control will prevent it from operating.

2.  Refrigerant:  In most cases a loose fitting or crack in the refrigerant line set will leak the refrigerant that will have an oily feel.  You should call a HVAC professional to check the system.  Most systems will need to have the line sets vacuumed to remove any contamination that may have entered a crack and re-charged to manufacture settings.  This takes a special set of gauges for either R22 or R410A.

Compare Mini Splits and Central Air Conditioners

Many consumers are weighing the pros and cons between mini split air conditioners and central air conditioners. I will try to lay out the major differences between the two systems and try to help you make the right decision for your home or office.

Space Requirements: I am going to break this down into two sections: Square feet to be cooled and Ceiling Height.

If you need an air conditioner to cool multiple rooms in a large area, I would recommend a central air conditioner. Mini split systems are great to cool areas and additions. They generally max out at 1,200 square feet. The cool air expelled by a mini split air conditioner can only reach areas of your home that are not closed off. If you have multiple rooms with doors, it will be very difficult for them to be cooled by a mini split system. You can purchase mini split systems with dual or multiple indoor evaporators, but the cost is driven up considerably. Single rooms and additions better suit mini split applications.

Ceiling height is the other variable that you need to consider when choosing between the two styles of air conditioners. A central air conditioner requires ductwork to distribute the air to each desired area. Standard ductwork requires approximately 12” of height for installation. Many older homes and basements do not have enough ceiling height to comfortably fit the additional ductwork. In these cases a ductless mini split air conditioner would be ideal.

Efficiency: Both the central air and mini split air conditioners have high-efficiency standards. In fact they were placed in the same split system certification. Make sure to check SEER ratings when purchasing your air conditioner. The higher the SEER the more efficient the unit. Currently 13 SEER is the minimum for the United States.

Central air conditioners do efficiency by having long duct runs, leaks and extra registers. If you are trying to cool your sunroom to 72° F you may have to lower your thermostat for the whole house to 65° F. This is not a very efficient way to cool an area. In this case an additional mini split air conditioner would be an excellent solution.

Price: Of course price is usually the biggest concern for consumers when deciding between a central air conditioner and a ductless mini split. Central air conditioners and large mini split air conditioners are very similar in price for the equipment. A major difference is that consumers can shop online for a ductless air conditioner, but by law they have to buy a central air conditioner from a contractor. This gives the consumer the ability to shop and save on equipment online.

The addition of ductwork and the increased labor really adds to the central air conditioners final price. The more ductwork that needs to be run, the more money it will cost for installation. You save this money with the purchase of a ductless mini split air conditioner. Ductless air conditioners can be installed professionally between $300 and $900 (depending on how far the outdoor unit sits from the indoor unit), and if you are able to do some of the basic labor. Both units require the addition of electricity, so make sure to find an installer that can work with both HVAC and electricity.

For more information on ductless mini split air conditioners, please check out our other articles online.

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Why is my evaporator icing up?

Reasons why evaporator is icing up:

A. Filters may be dirty. Take filters out of the evaporator unit and clean.
B. Run the fan only without the cool mode or heat mode. This process heats the unit and will melt the ice.
C. After the ice on the evaporator has melted the unit should operate properly.

Why am I getting moisture from my indoor evaporator unit?

Most units have a drain pan. At time of installation a mini split air conditioner needs to be angled a ¼” down towards the drain line to help empty the drain pan. Window units need to angled a ¼” from front to back. Ductless systems use gravity to drain condensation, which is a byproduct of air conditioning. Make sure that the drain pan can properly empty by angling the unit.

Things to check if my unit is properly positioned:
A.  Check the drain line for blockage (dirt, leaves, etc.). If you have a blockage take the line off the unit and clean.
B.  Check to make sure drain line is connected to unit properly.
C.  Check for cracks or holes in the drain line.

Why is my indoor evaporator fan not working?

Fan in indoor unit: Start by using the remote to put the unit in fan mode. If the indoor fan starts operating this is the normal response.

If the fan does not operate at this time check these solutions:

A. Make sure the timer function on the remote is not on.  If timer function is on use remote to deactivate.
B. Fan motor could be defective.  Check for short windings or open windings.  Must replace fan motor if these symptoms are found.
C. Fan capacitor needs a capacitor checker for this one.
D. Faulty control board, need to replace control board.

Why is my remote not controlling my ductless air conditioner?

Remote:  When turning on the remote you should hear a beep from the indoor unit.  If you hear the beep the remote is in working condition.  The unit will not beep when turned on.

Things to check when this happens:

A. Faulty remote, replace batteries if this is not the cause replace remote.
B. Blown fuse on the indoor control board.  Remove control board from indoor unit and replace.
C. Indoor unit is not receiving power.  Check the line voltage between the terminals.
D. The indoor board could be faulty, replace indoor board.

Inverter Compressor Benefits in a Mini Split Air Conditioner

Shopping for a mini split air conditioner got a little more difficult in the past couple of years. With the new federal regulations on minimum SEER ratings in the United States, manufacturers have started using inverter compressors to obtain 13 SEER or higher. This has created exceptional efficiency in wall mounted air conditioners, but also has increased the consumer cost.

The compressor is the heart and soul of every mini split air conditioner. It is the most essential component in an air conditioner and the most expensive. When purchasing a mini split air conditioner make sure to find a system with a solid warranty approximately 5 years in length. Also, make sure to purchase your mini split from a company that has parts available in the United States. Some companies can take up to three weeks to ship parts if they have to order them overseas.

I have read many articles talking about inverter compressors versus standard rotary compressors, but I think this sums it up best. A standard rotary or scroll compressor operates like a light switch: either on or off and nothing in between. An inverter compressor operates like a water faucet: it only uses enough power to reach the desired setting.

An inverter compressor is programmed to run at optimum speed, which is regulated by the input frequency as it varies between heat load requirements. Example: Your mini split is set at 72° F. The room becomes hot and the compressor needs to cool it by a couple of degrees. A standard compressor will turn “On” with full power, while an inverter compressor only uses enough resources (RPM) to reduce the room’s temperature to the desired setting.

Over a full day of operation, a standard compressor will have to turn on and off a substantial number of times. An inverter compressor will turn on and reach the desired setting and then idle at that setting until needed further.

By using different rotation speed, the inverter compressor is saving energy and operating more quietly than the standard compressor. Not having to constantly turn on and off at maximum RPM increases the lifespan of the inverter compressor.

When a large temperature change is needed, the inverter compressor can operate at a much higher RPM speed than the standard compressor, reducing the amount of run time and reducing your energy costs. Some researchers show a reduced power consumption as much as 60% versus a fixed speed standard compressor.

Inverter compressors offer a more precise temperature control for your mini split air conditioner. I hope this helps you understand how an inverter compressor operates and will help you make a decision with your ductless air conditioner purchase.

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Friedrich Window Air Conditioner Leaking Water

Greg, L. Writes:

Problem:

I have water leaking from the air conditioner on the floor in front of it.  Do you know what could be causing it?

Answer:

Most units have a drain pan. At time of installation a mini split air conditioner needs to be angled a ¼” down towards the drain line to help empty the drain pan. Window units need to angled a ¼” from front to back. Ductless systems use gravity to drain condensation, which is a byproduct of air conditioning. Make sure that the drain pan can properly empty by angling the unit.

Things to check if my unit is properly positioned:
A.  Check the drain line for blockage (dirt, leaves, etc.). If you have a blockage take the line off the unit and clean.
B.  Check to make sure drain line is connected to unit properly.
C.  Check for cracks or holes in the drain line.

Ductless Mini Split Preventative Maintenance

“If you must cover your air conditioner leave the side vents clear to let air circulate.”

Preventative maintenance is an important factor to increase the life span of your ductless air conditioner and reduce break downs. Every year there are a few little things that you can do to make a big difference.

Here are a few tips to increase the life of your air conditioner:

The outdoor condenser should always remain clear of sticks, garbage or other debris that can fit through the protective grille and damage the fan or compressor. Most condenser fan blades are made of plastic and can easily be broken by items fitting through the grille.

When mowing the lawn make a conscious effort to blow grass away from the condenser and cut back long weeds that grow around the unit.

Once a year you should spray out the condenser with a hose or a bucket of water and let dry without use for at least 24 hours. I like to remove the few bolts on top of the condenser and remove top cover. When the cover is removed I can easily see any damage or debris inside the condenser.

Check the copper piping inside the condenser and line set connections on the side of the condenser for any oily residue. Refrigerant leaks leave an oily residue and a quick check once a year can save you hundreds in repair costs. Manufacture warranties will not cover the air conditioners compressor if it is operated low on refrigerant.

The last preventative maintenance I do on the condenser is to make sure the unit is still level. Over time condensers can sink and become uneven. Non-level condensers are a quick death for the units compressor.

I also get questions from consumers about covering the condenser in the off-season in areas with snow fall or other unsightly weather. I do not agree with the idea that covering your condenser helps prevent rust. In fact, when condensers are covered moisture builds up inside the unit and fresh air doesn’t have a chance to dry the unit. If you must cover your air conditioner leave the side vents clear to let air circulate.

Moisture = Rust

We all rely on our air conditioners to come to life when the weather gets hot and unbearable, follow these few preventative maintenance tips and you will not be disappointed.

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Benefits of Ductless Mini Split Air Conditioners

The popularity of wall mounted mini split air conditioners around the world is evidence that ductless equipment is here to stay. The United States has jumped on board and contractors and consumers keep finding new and ingenious ways of using ductless equipment.

Following is a list of benefits for using ductless air conditioning equipment:

Cost: A competitive United States ductless market has helped drive prices down and efficiency up. You can call your local contractor or go online and find excellent pricing on ductless equipment. You can find mini split units for less than $1,000.00 and many cities offer rebates for high-efficiency air conditioners.

Installation: Installation of ductless equipment is very clean and easy. Most ductless mini split air conditioners only require a 3” hole in the wall to run all the needed refrigerant line sets and electrical wiring. Most contractors can fully complete the job in less than 4 hours, if the outdoor condenser shares the same wall with the indoor evaporator.

Space Requirement: Many older homes, cabins and additions were not built with central air conditioning in mind and do not have adequate space for ductwork. Wall mounted mini split air conditioners negate the need for added ductwork. Refrigerant line sets and wiring can easily run through attics, walls and ceilings to connect with the outdoor condenser.

Efficiency: Ductless split systems have become increasingly more efficient since United States minimum requirements rose to 13 SEER. It is not uncommon to find ductless equipment exceeding 20 SEER. Many ductwork systems lose more than 15% of the conditioned air through leaks and cracks.

Zone Control: Many mini split owners already have an existing central air conditioner system in their home. Smaller central air conditioners and older equipment are expensive to replace and many consumers have purchased mini split air conditioners to cool areas that their existing systems can’t handle. Mini split air conditioners have the ability to cool any area or zone in a building. Why keep your central air conditioner at 65° F to cool your sunroom or upper level to 75°F? Installing a mini split unit in these areas is an efficient solution.

Heating Capabilities: Many ductless mini split systems offer either heat pump or electric heat functions. This is an excellent added feature for areas that require heat during the year and either do not have a furnace or the furnace isn’t capable of adequately warming the area.

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