diff --git a/src/I8Beef.Ecobee.TestClient/Program.cs b/src/I8Beef.Ecobee.TestClient/Program.cs
index 1a4e8b6..3d21b9b 100644
--- a/src/I8Beef.Ecobee.TestClient/Program.cs
+++ b/src/I8Beef.Ecobee.TestClient/Program.cs
@@ -1,6 +1,9 @@
+using I8Beef.Ecobee.Protocol;
 using I8Beef.Ecobee.Protocol.Thermostat;
 using System;
+using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -86,31 +89,38 @@ private static async Task Main()
             //Console.WriteLine();
             //Console.WriteLine(JsonSerializer<ThermostatResponse>.Serialize(thermoResponse));
 
-            // Set thermostat fan
-            //Console.WriteLine("Setting thermostat fan hold");
-
-            //var themroFanRequest = new ThermostatUpdateRequest
+            //var thermostat = thermoResponse.ThermostatList.FirstOrDefault();
+            //if (thermostat != null)
             //{
-            //    Selection = new Protocol.Objects.Selection
-            //    {
-            //        SelectionType = "registered"
-            //    },
-            //    Functions = new List<Protocol.Objects.Function>
+            //    // Set thermostat fan
+            //    Console.WriteLine("Setting thermostat fan hold");
+
+            //    var themroFanRequest = new ThermostatUpdateRequest
             //    {
-            //        new Protocol.Functions.SetHoldFunction
+            //        Selection = new Protocol.Objects.Selection
             //        {
-            //            Params = new Protocol.Functions.SetHoldParams
+            //            SelectionType = "registered"
+            //        },
+            //        Functions = new List<Protocol.Objects.Function>
+            //        {
+            //            new Protocol.Functions.SetHoldFunction
             //            {
-            //                HoldType = "nextTransition",
-            //                Fan = "on"
+            //                Params = new Protocol.Functions.SetHoldParams
+            //                {
+            //                    HoldType = "nextTransition",
+            //                    //CoolHoldTemp = thermostat.Runtime.DesiredCool,
+            //                    //HeatHoldTemp = thermostat.Runtime.DesiredHeat,
+            //                    Fan = "on"
+            //                }
             //            }
             //        }
-            //    }
-            //};
+            //    };
+
+            //    var themroFanResponse = await client.PostAsync<ThermostatUpdateRequest, Response>(themroFanRequest);
+            //    Console.WriteLine();
+            //    Console.WriteLine(JsonSerializer<Response>.Serialize(themroFanResponse));
+            //}
 
-            //var themroFanResponse = await client.PostAsync<ThermostatUpdateRequest, Response>(themroFanRequest);
-            //Console.WriteLine();
-            //Console.WriteLine(JsonSerializer<Response>.Serialize(themroFanResponse));
 
             Console.ReadLine();
         }
diff --git a/src/I8Beef.Ecobee/Protocol/Objects/Functions/SetHoldParams.cs b/src/I8Beef.Ecobee/Protocol/Objects/Functions/SetHoldParams.cs
index 23b364d..d2af39f 100644
--- a/src/I8Beef.Ecobee/Protocol/Objects/Functions/SetHoldParams.cs
+++ b/src/I8Beef.Ecobee/Protocol/Objects/Functions/SetHoldParams.cs
@@ -12,19 +12,19 @@ public class SetHoldParams : FunctionParams
         /// <summary>
         /// The temperature to set the cool hold at.
         /// </summary>
-        [JsonProperty(PropertyName = "coolHoldTemp", Required = Required.Always)]
-        public int CoolHoldTemp { get; set; }
+        [JsonProperty(PropertyName = "coolHoldTemp", NullValueHandling = NullValueHandling.Ignore)]
+        public int? CoolHoldTemp { get; set; }
 
         /// <summary>
         /// The temperature to set the heat hold at.
         /// </summary>
-        [JsonProperty(PropertyName = "heatHoldTemp", Required = Required.Always)]
-        public int HeatHoldTemp { get; set; }
+        [JsonProperty(PropertyName = "heatHoldTemp", NullValueHandling = NullValueHandling.Ignore)]
+        public int? HeatHoldTemp { get; set; }
 
         /// <summary>
         /// The fan state.
         /// </summary>
-        [JsonProperty(PropertyName = "fan")]
+        [JsonProperty(PropertyName = "fan", NullValueHandling = NullValueHandling.Ignore)]
         public string Fan { get; set; }
 
         /// <summary>
@@ -32,44 +32,44 @@ public class SetHoldParams : FunctionParams
         /// settings for this hold. If this value is passed the coolHoldTemp and heatHoldTemp
         /// are not required.
         /// </summary>
-        [JsonProperty(PropertyName = "holdClimateRef")]
+        [JsonProperty(PropertyName = "holdClimateRef", NullValueHandling = NullValueHandling.Ignore)]
         public string HoldClimateRef { get; set; }
 
         /// <summary>
         /// The start date in thermostat time.
         /// </summary>
-        [JsonProperty(PropertyName = "startDate")]
+        [JsonProperty(PropertyName = "startDate", NullValueHandling = NullValueHandling.Ignore)]
         public string StartDate { get; set; }
 
         /// <summary>
         /// The start time in thermostat time.
         /// </summary>
-        [JsonProperty(PropertyName = "startTime")]
+        [JsonProperty(PropertyName = "startTime", NullValueHandling = NullValueHandling.Ignore)]
         public string StartTime { get; set; }
 
         /// <summary>
         /// The end date in thermostat time.
         /// </summary>
-        [JsonProperty(PropertyName = "endDate")]
+        [JsonProperty(PropertyName = "endDate", NullValueHandling = NullValueHandling.Ignore)]
         public string EndDate { get; set; }
 
         /// <summary>
         /// The end time in thermostat time.
         /// </summary>
-        [JsonProperty(PropertyName = "endTime")]
+        [JsonProperty(PropertyName = "endTime", NullValueHandling = NullValueHandling.Ignore)]
         public string EndTime { get; set; }
 
         /// <summary>
         /// The hold duration type. Valid values: dateTime, nextTransition, indefinite,
         /// holdHours.
         /// </summary>
-        [JsonProperty(PropertyName = "holdType")]
+        [JsonProperty(PropertyName = "holdType", NullValueHandling = NullValueHandling.Ignore)]
         public string HoldType { get; set; }
 
         /// <summary>
         /// The number of hours to hold for, used and required if holdType='holdHours'.
         /// </summary>
-        [JsonProperty(PropertyName = "holdHours")]
-        public int HoldHours { get; set; }
+        [JsonProperty(PropertyName = "holdHours", NullValueHandling = NullValueHandling.Ignore)]
+        public int? HoldHours { get; set; }
     }
 }